HomeMy WebLinkAbout7/29/2020 cc - Otto (NACTO Guidelines for Speed Limits)
Wilbanks, Megan
From:Garrett Otto <
To:Advisory Bodies
Cc:Fukushima, Adam
Subject:ATC - Proposed policy and guidelines for setting safe speed limits
Dear ATC members,
I think it would be appropriate to include NACTO's recent guideline for setting safe speed limits into the ATP.
https://nacto.org/2020/07/22/nacto-announces-new-framework-to-set-safe-speed-limits/
Statewide, there have been discussions about adjusting the way cities are allowed to set speed limits with firm data to
show that 85th percentile is only leading to higher speeds and death. See the report and recommendation here.
We need to be ready and willing to set safe speed limits throughout the city if we want to truly meet our vision zero
goals and make our street feel safer. We have advocated many times to include a maximum speed limit on all city
streets and these reports are just the sort of backing that we need for SLO to justify reducing speed limits. I think we are
just around the corner at the state level to be able to set more appropriate speed limits, so lets make sure ATP and
circulation element are ready to adapt.
I think it is pertinent to include a goal/policy in the ATP to "explore implementing universal speed limit of 20MPH on all
residential and collector streets, 15MPH around sensitive areas such as schools and parks, and a maximum speed limit of
30MPH on any street with city limits." Please include something to this extent into the draft ATP for the ATC consider.
Thanks
Garrett Otto
Bike SLO County
1
7/29/2020 NACTO Releases City Limits, an Innovative Framework to Set Safe Speed Limits on City Streets | National Association of City Transport…
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NACTO Releases City Limits, an Innovative
Framework to Set Safe Speed Limits on
City Streets
Jul 22, 2020
Over 35,000 people die on U.S. roadways every year, at a rate twice as high as
peer countries
Current speed limit setting practice results in unsafe streets; new NACTO
guidelines outline how to use a tested and proven safe systems approach to set
safer speed limits in urban areas
Speeds and crash severity have increased on many streets during the
coronavirus pandemic, underlining the importance of safer speed limits
For Immediate Release | July 22, 2020
Contact: Alex Engel | alex@nacto.org
Guidance Available Online: nacto.org/safespeeds (https://nacto.org/safespeeds/)
The National Association of City Transportation O cials (NACTO), today released an innovative, tested, and
proven framework for setting safe speed limits for city streets. Developed by a steering committee of
NACTO’s 86 member cities and transit agencies, City Limits outlines how to use a safe systems approach to
set speed limits in urban environments, in contrast to legacy methods (e.g. the 85th percentile) that often
result in speeds that are inappropriately fast for urban environments.
City Limits outlines a three-method approach to speed limit setting that provides an alternative to
percentile-based speed limit setting:
1. Setting default speed limits on many streets at once (such as 25 mph on all major streets and 20
mph on all minor streets),
2. Designating slow zones in sensitive areas, and
3. Setting corridor speed limits on high priority major streets, using a safe speed study, which uses
conflict density and activity level to set context-appropriate speed limits.
The methods outlined in City Limits can be combined, and, unlike percentile-based approaches, each is
context-sensitive, allowing cities to holistically evaluate who is using streets and how people are using
them, from people walking and biking, to those taking transit or visiting a school. The guidance ranges
7/29/2020 NACTO Releases City Limits, an Innovative Framework to Set Safe Speed Limits on City Streets | National Association of City Transport…
https://nacto.org/2020/07/22/nacto-announces-new-framework-to-set-safe-speed-limits/2/6
from step-by-step checklists for conducting activity level & conflict density analyses, to nuanced metrics
for documenting speeds that go beyond percentile-based speed setting practices.
Over 35,000 people die on US roads every year, a tra c safety crisis unmatched in severity by the US’s
industrialized peers. Speed is what most often turns a crash deadly. A person hit by a car traveling at 35
miles per hour is ve times more likely to die than a person hit at 20 miles per hour. Yet, speed limits in
the US are often set in a process that largely ignores anyone outside of a car.
“Most speeds limits are set using an oversimpli ed and outdated method: measure 100 drivers traveling
without any tra c and set the speed limit based on the 15th-fastest driver,” said Jenny O’Connell, NACTO
Program Manager. “If this sounds like a system that would create dangerous outcomes, that’s because it
does. Even worse, in many cases, speeds ramp up over time as drivers respond to speed limit signs and
speed a few miles per hour over the posted limit, creating a negative feedback loop of faster, less safe
streets.”
In many areas, cities rely on police enforcement to compensate for a lack of flexibility in engineering and
speed limit setting policies, a practice that is not proven to reduce tra c injuries or fatalities and often
increases risk for Black people and other people of color on city streets. A growing body of evidence shows
that speed limit changes alone can lead to measurable declines in speeds and crashes, even absent
enforcement or engineering changes.
The importance of safe speed limit setting has been underscored in recent months by e ects from the
coronavirus pandemic. As people traveled less during stay-at-home orders, speeds increased to even more
unsafe levels. In May, tra c across the U.S. was 41% lower than pre-pandemic volumes
(https://www.washingtonpost.com/local/tra candcommuting/the-coronavirus-pandemic-emptied-
americas-highways-now-speeders-have-taken-over/2020/05/10/c98d570c-8bb4-11ea-9dfd-
990f9dcc71fc_story.html), yet crashes only dropped 21%, meaning each trip was riskier
(https://www.nsc.org/in-the-newsroom/motor-vehicle-fatality-rates-rose-235-in-may-despite-quarantines).
“Context-sensitive speed limit setting means that safe speeds are chosen based on how a street is used,
and the important functions it plays in a community,” said Corinne Kisner, NACTO Executive Director. “An
increasing number of cities are moving beyond the flawed assumptions in the 85th percentile approach,
and have developed new ways to set speed limits. We’re proud to have worked with these cities to
document and codify these groundbreaking approaches, which have already saved many lives, and have
the potential to save thousands more every year.”
“Slower is safer. In Minneapolis, we are lowering our residential speed limit to 20 mph, and our major
streets to 25 mph because we know it will save lives,” said Robin Hutcheson, Minneapolis Director of
Public Works and NACTO President. “NACTO’s new guidance will help cities across the country use a
modern, adaptive approach to speed limit setting that centers safety—not speed—as the primary goal.
City Limits reflects intense e ort from city sta who are doing the work every day, and provides expert
guidance for cities to prioritize the safety of people traveling, especially our most vulnerable users.”
“Among New York City’s very rst Vision Zero accomplishments in 2014 were persuading our State
Legislature to allow us to lower our default speed limit to from 30 mph to 25 mph and to expand our
automated enforcement program. Both have been central to the progress we have made since then in
reducing fatalities,” said New York City Transportation Commissioner Polly Trottenberg. “Speed
management is the number one priority in roadway safety. Vehicles traveling at safer speeds are far less
likely to be involved in fatal crashes. I thank the team at NACTO for providing the detailed guidance of City
Limits, an invaluable resource on how to achieve safer speed limits—and save lives on our nation’s streets.”
7/29/2020 NACTO Releases City Limits, an Innovative Framework to Set Safe Speed Limits on City Streets | National Association of City Transport…
https://nacto.org/2020/07/22/nacto-announces-new-framework-to-set-safe-speed-limits/3/6
“The City of Atlanta is excited about the release of NACTO’s speed limit setting guidance,” said Josh
Rowan, Commissioner of the Atlanta Department of Transportation. “We recently adopted Vision Zero
and legislated a default 25 MPH speed limit on certain city-controlled streets. This guidance has been and
will continue to be bene cial in establishing safe speed limits on our urban arterial streets that feel and
function like suburban roads, where using the traditional 85th percentile methodology will only lead to
higher speed limits being set. NACTO continues to be a leader in urban street design and forges the way
for many cities like us to create safer streets and move closer to realizing zero fatalities.”
“As vehicle speeds increase above 15 mph, crashes quickly get deadly. If you’re hit by a car at 15 mph, you’ll
likely recover. At 45 mph, you’re dead. Reducing speeds is a critical step to saving lives,” said Je rey
Tumlin, Director of Transportation, San Francisco Municipal Transportation Agency (SFMTA). “NACTO has
elevated the importance of this necessary strategy. In California, we continue to pursue legislative action
for setting rational speed limits. NACTO’s guidance provides national leadership on this critical issue.”
“The traditional method of setting speed limits based on the 85th percentile ignores many realities of
cities, particularly the connection to nearby land uses,” said Joseph Barr, Cambridge Director of Tra c,
Parking, and Transportation and NACTO Board Member. “We’re thrilled to support City Limits, which
outlines methodologies for setting speeds that put the safety of people front and center. This guidance
will help cities move from a percentile-based system that rewards unsafe speeding towards one that helps
achieve a safer environment for everyone using city streets.”
“Traditional transportation design has focused on designing streets and roadways for speeds that are
generally inappropriate, especially in an urban context, contributing to unnecessary loss of life and serious
injuries,” said Billy Hattaway, Transportation Director, City of Orlando. “Practitioners need guidance on
reducing posted speeds and managing speed to improve safety for all users, especially vulnerable users
such as pedestrians and bicyclists. This is an essential guide to support that goal.”
“A safe street is not one where safety is determined by how fast someone can comfortably drive, but
rather one where a person can comfortably walk, ride a bike, and cross the street using a wheelchair,” said
Ryan Noles, Senior Transportation Planner, City of Boulder. “City Limits creates a framework to move
beyond setting speed limits using the 85th percentile, to a place where cities can set speed limits that
prioritize policy goals. Boulder is proud to have already adopted a 20 mph default speed limit across the
city, and going forward we will be working to meet the intent of that policy and make our streets slower,
and safer, for everyone.”
“It’s crucial that cities inform and inspire each other as we work towards Vision Zero,” said Chris Warner,
Transportation Director for the City of Portland, Oregon. “I’m proud to work with cities that collaborate
and bring the nation’s best ideas to their local communities. In Portland, we reduced the speed limit on
most city streets to 20 mph in Portland with broad public support. By working together, we can save lives,
while making our cities more vibrant and sustainable.”
“Addressing dangerous speeding is the only way for everyone to get around safely,” said Sam Zimbabwe,
Director of the Seattle Department of Transportation. “As we design a transportation network that serves
everyone, we have to prioritize saving lives as we manage our streets.”
“From 2010 to 2019, most Washingtonians killed while walking or biking (87%) died on roads with a posted
speed of 30 mph or higher. To tackle this critical problem, WSDOT is leading a multi-agency,
multidisciplinary group working on a model policy addressing speed management for injury minimization,”
said Keith Metcalf, Deputy Secretary, Washington State Department of Transportation. “We know we
need to apply design tools and create ‘self-enforcing’ streets that help drivers move at speeds appropriate
to the context. We want to be a partner with our cities and counties in saving lives, and City Limits will help
us work with them.”
7/29/2020 NACTO Releases City Limits, an Innovative Framework to Set Safe Speed Limits on City Streets | National Association of City Transport…
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“Thank you to NACTO for publishing this guide, and elevating the signi cant relationship between speed
and safety for all road users,” said Stephanie Pollack, Secretary and CEO, Massachusetts Department of
Transportation. “This guidance comes at an especially important time as the rate of fatal crashes has
increased during COVID and we need safer speeds to prevent serious injuries and fatalities.”
“ITE congratulates NACTO on the development and publication of this important new speed management
resource,” said Je Paniati, Executive Director and CEO of ITE. “Determining and achieving context-
appropriate target speeds on urban streets is essential to the vision of zero fatalities and serious injuries.”
“The top priority in our nation’s transportation policy and program is to let vehicles go fast. It has ltered
into every level of implementation, down to the way we set speed limits. We raise the speed limit to suit
the speeders, as long as there are enough of them (and it doesn’t take that many),” said Beth Osborne,
Director of Transportation for America. “NACTO once again provides excellent guidance to practitioners
who recognize the problem and who want to put safety ahead of speed.”
“The soaring number of pedestrian deaths we’ve seen in recent years is a wake-up call for a new approach
to vehicle speeds in urban areas,” said Jessica Cicchino, Vice President for Research at the Insurance
Institute for Highway Safety (IIHS). “IIHS research demonstrates that lowering city speed limits curbs the
most dangerous speeding and can make the roads safer for everyone who drives, walks, or bikes.”
“To advance Vision Zero, nothing is more important than managing speeds,” said Leah Shahum, Founder &
Director, Vision Zero Network. “For too long, cities have been hindered from setting speeds to promote
safe mobility for all. This resource will help usher in a new day of safety on our streets, especially our most
vulnerable—children, seniors, and people walking and biking.”
City Limits is available as a free resource at nacto.org/safespeeds (https://nacto.org/safespeeds/).
###
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CalSTA Report of Findings
AB 2363
Zero Traffic Fatalities Task Force
January 2020
AB 2363 Zero Traffic Fatalities Task Force
CalSTA Report of Findings
i
Table of Contents
1.0 Executive Summary ............................................................................................................. 1
2.0 Introduction and Background ............................................................................................... 3
2.1. Traffic Fatalities and Injuries, Speed, and Safety ......................................................... 3
2.2. Trends, Context, and Considerations ........................................................................... 6
2.3. The 85th Percentile Speed – An Overview .................................................................... 7
2.4. AB 2363 – Zero Traffic Fatalities Task Force ............................................................... 8
2.5. Zero Traffic Fatalities Task Force and Advisory Group Members ................................ 9
2.6. Report of Findings – Approach and Timeline ............................................................. 10
3.0 Establishing and Adjusting Speed Limits in California ....................................................... 13
3.1. Authority to Establish Speed Limits ............................................................................ 13
3.2. Types of Speed Limits ................................................................................................ 13
3.3. Establishing and Deviating from Speed Limits ........................................................... 14
3.4. Engineering and Traffic Surveys – An Overview ........................................................ 18
3.5. Adjusting Speed Limits from the 85th Percentile Speed .............................................. 20
4.0 The 85th Percentile Speed Methodology – An Analysis ..................................................... 23
4.1. History, Evolution, and Limitations of the Idea ............................................................ 23
4.2. Using the 85th Percentile in Urban and Rural Settings ................................................ 24
4.3. Effect of Bicycle and Pedestrian Plans on the 85th Percentile .................................... 25
5.0 Alternatives to the 85th Percentile – Local, State, National, and International Trends in
Setting Speed Limits .......................................................................................................... 27
5.1. Summary ..................................................................................................................... 27
5.2. International Trends .................................................................................................... 28
5.3. Recent National Trends .............................................................................................. 30
5.4. Conclusion: Shifting Paradigms .................................................................................. 32
6.0 Engineering and Designing for Safety – Roads and Vehicles ........................................... 33
6.1. Engineering Countermeasures ................................................................................... 33
6.2. Emerging Vehicle Technologies ................................................................................. 40
7.0 Speed Enforcement ........................................................................................................... 43
7.1. Overview of Speed Enforcement ................................................................................ 43
7.2. Automated Speed Enforcement .................................................................................. 44
7.3. High Visibility Enforcement ......................................................................................... 47
8.0 Additional Steps to Improve Safety .................................................................................... 49
8.1. Improving Education through Funding Allocations ..................................................... 49
8.2. Improving Safety Data ................................................................................................ 50
8.3. Linking Crash and Medical Data ................................................................................. 51
9.0 Findings and Recommendations for Policy Consideration ................................................ 53
9.1. Establishing Speed Limits (S) – Findings and Recommendations for Policy
Consideration ..................................................................................................................... 54
9.2. Engineering (EN) – Findings and Recommendations for Policy Consideration .......... 60
9.4. Education (ED) – Findings and Recommendations for Policy Consideration ............. 66
10.0 Appendices ........................................................................................................................ 67
A. AB 2363 – Zero Traffic Fatalities Task Force ................................................................ 67
B. University of California, Institute of Transportation Studies, Research Synthesis ......... 68
C. List of Abbreviations ...................................................................................................... 69
AB 2363 Zero Traffic Fatalities Task Force
CalSTA Report of Findings
ii
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AB 2363 Zero Traffic Fatalities Task Force
CalSTA Report of Findings
1
1.0 Executive Summary
While the overarching objective of the transportation system is to provide mobility,
transportation professionals dedicate significant resources to create a system that is
safe for all users. Yet transportation professionals and policy makers continue to grapple
with increases in road traffic fatalities, injuries, and crashes at the local, state, national,
and even global levels.
Today, the traditional notion that roads should be designed to maximize vehicle
throughput is increasingly challenged as cities and counties rethink the function and
purpose of their streets, the different needs of road users such as bicyclists, pedestrians,
and scooter users, and the exponential dangers of excessive speed. There is clear
evidence, supported by statistical analyses, that traffic fatalities and serious injuries
increase with individual vehicle speed.
While roadway safety has long been the primary consideration in establishing speed
limits, speeding-related fatalities continue to represent a large portion of California’s total
traffic fatalities. Current procedures for setting speeds limits in California rely on the 85th
percentile methodology, an approach developed decades ago for vehicles primarily on
rural roads. Although California has become highly urbanized and its roadways have
changed significantly, reflecting different modes of transportation including bicycling,
walking, and scooters, the method for setting speed limits has not been modified to
reflect these changes. And while the current methodology allows traffic engineers to
consider other factors when setting speed limits, the 85th percentile speed remains the
primary factor used in determining posted speed limits regardless of the intended use of
the street.
While the way that speed limits are calculated have remained essentially static, the
population, vehicles, and street uses have evolved over time. CalSTA’s vision is to
transform the lives of all Californians through a safe, accessible, low-carbon, 21st-
century multimodal transportation system. However, the 85th percentile methodology
relies on driver behavior. Greater flexibility in establishing speed limits would offer
agencies an expanded toolbox in order to better combat rising traffic fatalities and
injuries especially for the most vulnerable roadway users.
Consistent with international trends, other U.S. states, including Oregon, Washington,
and New York, are enabling their cities to lower their speed limits and are exploring
alternative methods to establish speed limits based on safety goals and local context
instead of the 85th percentile speed. California has the opportunity to evaluate how it
sets speed limits and explore new approaches that prioritize safety and meet the needs
of all road users. It also has the opportunity to offer agencies greater flexibility to
establish lower speed limits through the revision of speed-limit-setting procedures and
the expansion of special low-speed zones.
Additionally, the State can support other strategies to make its roadways safer and
reduce traffic fatalities to zero. These interventions include roadway infrastructure
changes through engineering, enhancing traffic safety enforcement, supporting public
education and traffic safety campaigns as well as practitioner-focused education, and
improving safety data to make better-informed policy and program decisions.
AB 2363 Zero Traffic Fatalities Task Force
CalSTA Report of Findings
2
Pursuant to AB 2363, Zero Traffic Fatalities Task Force, CalSTA convened a statewide
Task Force and conducted an academic research synthesis to identify findings and
recommendations for policy consideration to reduce traffic fatalities to zero. This Report
of Findings reflects the culmination of activities that CalSTA initiated in March 2019. The
findings and recommendations for policy consideration begin on page 53.
Exhibit 1-1 cross-references the topics mandated by AB 2363 with the pertinent
sections of this document.
Exhibit 1-1 – Crosswalk: AB 2363 Topics and Report of Findings
AB 2363 Topic Report Sections
1) The existing process for establishing speed limits, including a
detailed discussion on where speed limits are allowed to
deviate from the 85th percentile.
3.0
2) Existing policies on how to reduce speeds on local streets and
roads.
3.3., 3.4, 5.0, 6.1, 7.0
3) A recommendation as to whether an alternative to the use of
the 85th percentile as a method for determining speed limits
should be considered, and if so, what alternatives should be
looked at.
5.0, 9.0
4) Engineering recommendations on how to increase vehicular,
pedestrian, and bicycle safety.
6.0, 9.0
5) Additional steps that can be taken to eliminate vehicular,
pedestrian, and bicycle fatalities on the road.
7.0, 8.0, 9.0
6) Existing reports and analyses on calculating the 85th
percentile at the local, state, national, and international levels.
4.0
7) Usage of the 85th percentile in urban and rural settings. 4.2
8) How local bicycle and pedestrian plans affect the 85th
percentile.
4.3
AB 2363 Zero Traffic Fatalities Task Force
CalSTA Report of Findings
3
2.0 Introduction and Background
2.1. Traffic Fatalities and Injuries, Speed, and Safety
While the overarching objective of the transportation system is to provide mobility,
transportation professionals dedicate significant resources to create a system that is
safe for all users. Yet transportation professionals and policy makers continue to grapple
with increases in road traffic fatalities, injuries, and crashes at the local, state, national,
and even global levels. According to the World Health Organization, deaths from road
traffic crashes have continued to climb, reaching 1.35 million in 2016, and representing
the eighth leading cause of death globally.1
Within the U.S. in 2017, there were 37,133 people killed in motor vehicle traffic crashes.
Additionally, in the same year 2,746,000 people were injured.2 Traffic crashes have
economic costs as well, which was estimated at $242 billion nationally.3 In California,
nearly 3,600 people die each year in traffic crashes and more than 13,000 people are
severely injured.4 Collectively, these traffic crashes cost California over $53.5 billion.5
Many factors contribute to traffic fatalities and injuries, including speeding, distracted
driving, and impaired driving. However, the relationship between speeding and traffic
fatalities and injuries is an increasing subject of attention. Of the 37,133 traffic fatalities
in 2017, 9,717 (26%) were involved in crashes where at least one driver was speeding.
Nationwide, speeding contributes to approximately one-third of all motor vehicle
fatalities. 6 It is important to note that the notation of “speeding” for the purpose of crash
reporting includes vehicle speeds that are unsafe for conditions as well as in excess of
the speed limit; see Section 8.2 for more information.
Recent important studies have highlighted excessive speed as a key risk factor in road
traffic injuries and fatalities. According to a 2017 National Transportation Safety Board
(NTSB) report, speed increases crash risk in two ways: it increases the likelihood of
being involved in a crash and it increases the severity of injuries sustained by all road
users in a crash.7 While the relationship between speed and crash involvement is
complex, the relationship between speed and injury severity is consistent and direct.8
There is clear and convincing evidence, supported by statistical analyses, that crash
severity increases with individual vehicle speed.9
1 World Health Organization, Global Status Report on Road Safety 2018 (2018), vii.
2 National Highway Traffic Safety Administration (NHTSA), Summary of Motor Vehicle Crashes 2017 Data
(2019), 1.
3 Ibid., 5.
4 California Office of Traffic Safety, California Highway Safety Plan (2019), 5.
5 This estimate was calculated by the University of California, Institute for Transportation Studies using
Strategic Highway Safety Plan data and the National Safety Council’s Guide to Calculating Costs of
Motor-Vehicle Injuries.
6 National Highway Traffic Safety Administration (NHTSA), Summary of Motor Vehicle Crashes, 7.
7 National Transportation Safety Board (NTSB), Safety Study: Reducing Speed-Relating Crashes
Involving Passenger Vehicles (2017), ix.
8 Ibid.,12.
9 Federal Highway Administration (FHWA), Speed Concepts: Informational Guide (2009), 8.
AB 2363 Zero Traffic Fatalities Task Force
CalSTA Report of Findings
4
The relationship between speed and injury severity is especially critical for vulnerable
road users such as bicyclists and pedestrians. In the U.S., on average, a pedestrian is
killed in a motor vehicle crash every 88 minutes.10 In the event of a crash between a
vehicle and a pedestrian or bicyclist, the vehicle's speed will largely determine whether
the person hit will survive. Exhibit 2-1 depicts this relationship, demonstrating that the
faster a vehicle is traveling, the less likely it is that the person will survive.
Exhibit 2-1 – Relationship between Vehicle Speed, Crashes, and Fatalities11
For the purposes of crash reporting, “speeding” is used to identify vehicles that are
traveling at speeds which are: 1) unsafe for conditions or 2) exceed the speed limit.
Speeds that are unsafe for conditions are based on basic speed law which is defined as
driving at a speed greater than is reasonable or prudent considering weather, visibility,
traffic, and roadway conditions. Because the definition of speeding includes these two
different conditions, it is unknown to what degree exceeding a posted or statutory speed
limit contributes to the total number of speeding-related crashes.
In addition to the impact of absolute vehicle speed on both crash severity and crash
frequency, speed variance within a traffic flow is often cited as contributing to crash risk.
However, the University of California Institute of Transportation Studies (UC ITS)
Research Synthesis commissioned specifically for this report found that research on
speed variation and safety is limited and generally inconclusive. Furthermore, there is an
absence of research related to speed variation impacts on crash frequency or severity of
collisions involving pedestrians and bicyclists in urban environments.
10 NHTSA, Summary of Motor Vehicle Crashes 2017 Data (2017), 1.
11 Tefft, B.C. “Impact speed and a pedestrian’s risk of severe injury or death,” Accident Analysis &
Prevention 50 (2013), 871-878.
AB 2363 Zero Traffic Fatalities Task Force
CalSTA Report of Findings
5
Given the rise in traffic fatalities and injuries, the contributing role of excessive speed to
those crashes, and the particular vulnerability of pedestrians, bicyclists, and scooter
users, transportation professionals and policymakers in the U.S. are struggling to find
solutions to make roadways safer. The issue of speed limits and speed management is
an increasingly important topic among stakeholders as speeding has been repeatedly
demonstrated to be a main factor in crash injury and severity.
Speeding, however, is a multi-faceted problem. There are many factors that can
influence how fast drivers choose to operate their vehicles. These include the design of
the roadway, the road’s posted speed limit, the enforcement of speed limits, and the
driver’s behavior. In their efforts to get drivers to slow down, practitioners use multiple
tools, including lowering speed limits, increasing enforcement, and changing the
roadway infrastructure. Ultimately “any measures that can achieve reductions in average
operating speeds, including lower speed limits, enhanced enforcement, and
communications campaigns, as well as engineering measures, are expected to reduce
fatal and injury crashes.”12
While many consider road design and engineering the effective countermeasure to
reduce operating speed, many cities, including Portland, Seattle, and New York City,
have also lowered the posted speed limits on their roadways. Although some subject
matter experts maintain that lowering posted speed limits does not cause drivers to slow
down, recent research has indicated that this approach is effective. The UC ITS
research synthesis found that research studies clearly indicate speed limit changes
cause changes in drivers’ speed. Moreover, “reducing vehicle speed limits will likely
reduce vehicle speeds and improve safety across most road environments.”13 UC ITS
concluded that “even though reducing speed limits may only have a small effect on
vehicle speeds, those changes in speed result in meaningful safety improvements”
especially for vulnerable road users such as bicyclist and pedestrians.”14
Other studies support the finding that even a small change in vehicle operating speed
can have large safety impacts. According to one, “a reduction of 3 mph in average
operating speed on a road with a baseline average operating speed of 30 mph is
expected to produce a reduction of 27% in injury crashes and 49% in fatal crashes.”15
Furthermore, since pedestrians and bicyclists are particularly vulnerable to severe injury
and death when struck by higher-speed vehicles, “countermeasures aimed at reducing
vehicle speeds have the potential to save lives.”16 National research results, as well as
the results of the UC ITS research synthesis, support the notion, which is advocated by
many California cities and local governments, that lowering speed limits will make
streets safer.
In California and the rest of the U.S., establishing the speed limit is based on a long-
standing methodology known as the 85th percentile speed. This methodology is
discussed in Section 3.0 of this report. However, it is important to note that studies have
shown that using the 85th percentile speed to establish speed limits has actually
12 NHTSA, Countermeasures that Work: A Highway Safety Countermeasure Guide for State Highway
Safety Offices Ninth Edition (2017), 3-7.
13 University of California Institute of Transportation Studies (UC ITS), Research Synthesis for AB 2363
Zero Traffic Fatalities Task Force (2019), 23.
14 Ibid., 23.
15 NHTSA, Countermeasures that Work, 3-7.
16 Ibid., 8-7.
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increased drivers’ operating speeds as an “unintended consequence.”17 This approach
creates a phenomenon known as “speed creep,” in which higher speed limits prompt
motorists to drive faster, which in turn prompt higher speed limits.18
While recent research has shown that changing speed limits is an effective method for
reducing vehicle operating speeds and increasing road safety, the absolute magnitude of
operating speed changes from speed limit changes alone are small but meaningful.
Further, there are many broader trends and contexts to consider, including the inherent
trade-off between speed and safety, the safety advances presented by emerging vehicle
technologies, and recent statewide developments related to safety and transportation.
These trends and contexts are discussed in the next section.
2.2. Trends, Context, and Considerations
Historically in the U.S., roadways have been designed with vehicles in mind, as typical
design standards “tend to look at streets as thoroughfares for traffic and measure their
performance in terms of speed, delay, throughput and congestion.”19 The field of traffic
engineering has traditionally approached road design from the perspective of moving
vehicles from one point to another as quickly as possible. As highway networks
expanded to accommodate increasing numbers of vehicles in the first half of the 20th
century, early attempts to regulate speed for safety gave way to the “consistent focus on
improving traffic service for ever-expanding motor vehicle fleets.”20 According to the
FHWA, “the automobile has irrefutably altered the way in which transportation systems
and the built environment are designed and constructed, often at the expense of
pedestrians.”21
Today, the traditional notion that roads should be designed to maximize vehicle
throughput is increasingly challenged as cities rethink the function and purpose of their
streets, the different needs of road users such as bicyclists and pedestrians, and the
exponential dangers of excessive speed. Most cities today strive to make their streets
more complete, less dominated by driving, and safer.22 As NACTO puts it, “roadways
once conceived singularly as arterials for traffic have been recast and retrofitted as
public spaces crucial to the economic success, safety and vitality of the city.”23
This trend away from roads designed for vehicle throughput calls attention to the
contradiction between level of service and safety. Cities who wish to increase safety by
reducing vehicle operating speeds must often balance these needs with the desires of its
commuters who do not want an increase in traffic congestion and slower vehicle
throughput. As UC ITS researchers put it, the crux of this issue is “the intuitive trade-off
between speed and safety.”24
17 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 54.
18 Ibid., 54.
19 National Association of City Transportation Professionals (NACTO), Urban Street Design Guide (2012),
6.
20 UC ITS, Research Synthesis, 36.
21 NHTSA, How to Develop a Pedestrian Safety Action Plan (2009), 7.
22 UC ITS, Research Synthesis, 39.
23 NACTO, Urban Street Design Guide, 4.
24 UC ITS, Research Synthesis, 45.
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In the last several years, states across the U.S., including Washington and Oregon, are
adopting speed-limit-setting laws that grant local agencies more flexibility to lower posted
speeds within their jurisdictions. While these national developments in speed management
are fairly recent, international speed management programs began to develop best
practices in the mid-1990s that aimed to “minimize the severity of road traffic crashes
through such programs as Vision Zero, Sustainable Safety, and Safe Systems.”25
In addition to the countermeasures designed to improve safety by reducing vehicle
operating speeds, it is important to note that rapidly emerging vehicle technologies will
also likely impact safety. Already a considerable amount of research is beginning to
describe the safety benefits of various levels of emerging technology.26 These vehicle
technologies include forward collision warning (FCW), automatic emergency braking
(AEB), lane departure warning (LDW), intelligent speed adaptation (ISA), lane keeping
assistance (LKA), and blind spot warning (BSW) systems.
Generally, these enhanced safety features are designed to reduce traffic crashes and
fatalities and improve safety for both the vehicle occupants and non-occupants. A
recently AAA research synthesis found that while such features have their limitations,
“current and future vehicle safety systems have the potential to dramatically reduce the
number of crashes, injuries and fatalities on our roadways,” and that these systems, “if
installed on all vehicles, would have had the potential to help prevent or mitigate roughly
40% of all crashes involving passenger vehicles, and 37% of all injuries and 29% of all
fatalities that occurred in those crashes.”27 It will be important for transportation and
traffic safety professionals to track the latest vehicle safety technologies as they continue
to develop.
Within California, it is also critical to consider the work of the Zero Traffic Fatalities Task
Force within the broader context of the California Strategic Highway Safety Plan (SHSP).
The SHSP is a coordinated, data-driven safety plan that provides a comprehensive
framework for reducing fatalities and serious injuries on California’s public roads with a
goal of zero deaths. A federal requirement, the plan guides investment decisions
towards strategies and countermeasure with the most potential to save lives and prevent
injuries. Spearheaded by CalSTA and its departments, over 900 safety stakeholders
from across the state contributed to the original SHSP. The 2020-2024 SHSP has
recently been finalized and the SHSP Implementation Plan, which identifies specific
actions, is currently underway.
2.3. The 85th Percentile Speed – An Overview28
Drivers play an important role in how posted speed limits are set. Many U.S. states and
California rely on a long-standing and widespread methodology known as the 85th
percentile speed to establish speed limits. As its name implies, the 85th percentile speed
is the velocity at which 85% of vehicles drive at or below on any given road. This
approach was developed in the U.S. in the mid-20th century and is still the dominant
25 Ibid., 50.
26 Ibid., 69.
27 AAA Foundation for Traffic Safety, Potential Reductions in Crashes, Injuries, and Deaths from Large-
Scale Deployment of Advanced Driver Assistance Systems Research Brief (2018), 9.
28 This summary is drawn from numerous sources including: UC ITS’s Research Synthesis (2019);
FHWA’s Speed Concepts: Informational Guide (2009); FHWA’s Methods and Practices for Setting Speed
Limits (2012); and California Department of Transportation’s (Caltrans) California Manual for Setting
Speed Limits (2014).
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factor in how speed limits are set in the U.S today. The 85th percentile methodology
assumes that most drivers will drive at a safe and reasonable speed based on the road
conditions. It is also based on the idea that speed limits are safest when they conform to
the natural speed driven by most drivers and that uniform vehicle speeds increase safety
and reduce the risks for crashes.
Using the 85th percentile methodology to establish a posted speed limit is a two-step
process. First, traffic engineers calculate the 85th percentile speed for a given roadway
by conducting an engineering and traffic survey, also known as a speed or traffic survey.
Engineers select a roadway and measure the speed of free-flowing traffic with radar or
lidar guns. The survey results are then analyzed, yielding the speed at which 85% of the
drivers are traveling at or below.
However, the 85th percentile speed does not automatically become the speed limit that is
posted for that road. In the second step, engineers can apply rounding and adjustment
allowances based on a variety of other conditions, resulting in a speed limit that deviates
from the 85th percentile speed. California law places parameters and limits on these
deviations. When using engineering and traffic surveys to post lower speed limits, the
maximum amount that a posted speed limit can deviate from the 85th percentile speed is
7 mph. Ultimately, the speed at which 85% of road users drive at or below exercises a
profound influence on the final speed limit that is posted for the road. UC ITS refers to
this reliance on driver behavior as “crowdsourcing” speed limits.29
Section 4.0 contains a detailed analysis of the 85th percentile speed methodology
including its history, limitations, and usage in urban and rural settings.
2.4. AB 2363 – Zero Traffic Fatalities Task Force
AB 2363 (Friedman – Chapter 650, Statutes of 2018) directed the Secretary of
Transportation to establish and convene the Zero Traffic Fatalities Task Force. Based on
the Task Force’s efforts, the Secretary shall prepare and submit a report of findings to
the Legislature by January 1, 2020 on the following issues:
1) The existing process for establishing speed limits, including a detailed discussion
on where speed limits are allowed to deviate from the 85th percentile.
2) Existing policies on how to reduce speeds on local streets and roads.
3) A recommendation as to whether an alternative to the use of the 85th percentile
as a method for determining speed limits should be considered, and if so, what
alternatives should be looked at.
4) Engineering recommendations on how to increase vehicular, pedestrian, and
bicycle safety.
5) Additional steps that can be taken to eliminate vehicular, pedestrian, and bicycle
fatalities on the road.
6) Existing reports and analyses on calculating the 85th percentile at the local, state,
national, and international levels.
7) Usage of the 85th percentile in urban and rural settings.
8) How local bicycle and pedestrian plans affect the 85th percentile.
29 UC ITS, Research Synthesis, 27.
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2.5. Zero Traffic Fatalities Task Force and Advisory Group Members
CalSTA established and first convened the Task Force on June 25, 2019, which
included representatives from all of the mandated organizations as well as other
interested stakeholders. A list of Task Force members and their organization is
presented in Exhibit 2-2. In addition, CalSTA formed an Advisory Group designed to
provide subject matter expertise to the Task Force. A list of Advisory Group members
and their organization is presented in Exhibit 2-3.
Exhibit 2-2 – Task Force Members
Agency/Organization Task Force Member
AAA Southern California Hamid Bahadori, Manager, Transportation Policy and Programs
Amalgamated Transit Union and
Teamsters
Shane Gusman, Representative
American Association of Retired
Persons
Bob Prath, Executive and National Policy Council member
California Bicycle Coalition
(CalBike)
Dave Snyder,
Executive Director
California Highway Patrol James Epperson, Chief
California Walks (Cal Walks) Tony Dang, Executive Director
City of Fresno Jill Gormley,
Traffic Engineering Manager
City of Glendale Carl A. Povilaitis,
Chief of Police
City of Palm Springs Lisa Middleton, Councilmember
City of Sacramento Jennifer Donlon Wyant,
Transportation Planning Manager
City of San Jose Laura Wells,
Director, Department of Transportation
Department of Public Health Jeffery Rosenhall, Chief, Policy and Partnership Development
Unit
Department of Transportation Jeanie Ward-Waller, District 2 Director (Acting)
Electronic Frontier Foundation Lee Tien, Senior Staff Attorney
Los Angeles Department of
Transportation
Seleta Reynolds, General Manager
NACTO/California City
Transportation Initiative
Jenny O’Connell, Program Manager
Office of Traffic Safety Barbara Rooney, Director
Rural Counties Task Force Dan Landon, Executive Director Nevada County Transportation
Commission
San Francisco Municipal
Transportation Agency
Kate Breen,
Director of Government Affairs
Southern California Association of
Governments
Meghan Sahli-Wells,
Regional Council Member & Culver City Mayor
Safer Streets Los Angeles Jay Beeber, Founder
UC Berkeley – Institute of
Transportation Studies
Offer Grembek, Co-Director, UCB Safe Transportation Research
and Education Center
Vision Zero Network Leah Shahum, Founder and Director
Subject Matter Expert Rock E. Miller, Consultant – Traffic Engineering Expert Witness,
Safety, and Urban Bikeways implementation
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Exhibit 2-3 – Advisory Group Members
Agency/Organization Advisory Group Member
City and County of San Francisco,
Department of Public Health
Megan Wier,
Director of Program on Health, Equity and Sustainability
Arup Megan Gee, Civil and Environmental Engineer; Senior
Planner
City of Long Beach, Public Works Luke Klipp,
Special Projects Officer
City of Santa Clarita Gus Pivetti,
City Traffic Engineer
City of Santa Monica, Planning and
Community Development Department
Andrew Maximous,
Principal Traffic Engineer
County of Los Angeles, Public Works Mathew Dubiel,
Senior Civil Engineer
County of Los Angeles, Department of
Public Health
Jean Armbruster,
Director, PLACE Program
San Francisco Metropolitan
Transportation Commission
Shruti Hari,
Principal, Safety & Asset Management
Walk San Francisco Jodie Medeiros,
Executive Director
Remix Rachel Zack, Policy Strategist
Streetlight Data, Inc. Sean Co, Director of Special Projects
Subject Matter Expert Henry Coles III, Retired Mechanical Engineer
Subject Matter Expert Ribeka Toda, Traffic Safety Consultant
2.6. Report of Findings – Approach and Timeline
The findings and recommendations for policy consideration in this Report of Findings are
based on numerous sources including Task Force meetings, Advisory Group meetings,
a University of California academic research synthesis, market research, and results
from multiple surveys completed by the Task Force and the Advisory Group.
Exhibit 2-4 depicts the high-level approach that guided this effort and Exhibit 2-5
depicts the high-level timeline and corresponding activities.
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Exhibit 2-4 – High-Level Approach
Exhibit 2-5 – Timeline
Timeframe Activity
June 2019 Conduct Task Force Survey
June 25, 2019 Convene Task Force Meeting #1
July 2019 Conduct Advisory Group Survey
July 2019 Initiate Academic Research
August 21, 2019 Convene Task Force Meeting #2
September 12, 2019 Convene Advisory Group Focus Group
October 1, 2019 Conduct Market Research Webinar
October 22, 2019 Convene Task Force Meeting #3
October 2019 Conclude Academic Research
November 2019 • Develop Report
• Distribute Draft Findings and Recommendations for
Policy Consideration to Task Force for Comment
December 2019 Finalize Report
January 2020 Submit Report to Legislature
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3.0 Establishing and Adjusting Speed Limits in
California
This section describes how speed limits are established in California. It covers the
authority to set types, types of speed limits, establishing and deviating from speed limits,
and the role of engineering and traffic surveys in establishing speed limits.
3.1. Authority to Establish Speed Limits
Establishing speed limits on California roadways is a responsibility shared by different
state and local agencies. The California Department of Transportation (Caltrans) has
authority to establish speed limits on the State Highway System, but roadways outside of
the State Highway System generally fall under the responsibility of the respective city or
county. Allowing cities or counties to establish speed limits on the roadways under their
jurisdiction acknowledges the importance of recognizing unique local conditions when
setting speeds. The fact that multiple agencies are involved in establishing speed limits
contributes to the complexity of establishing standards while also respecting unique local
conditions. Ultimately, “speed management and the setting of appropriate speed limits
requires a coordinated effort among State and local highway safety offices, engineering
offices, and law enforcement agencies.”30
In California, the basis, principles, and methodology for establishing speed limits are
outlined in several source documents. The California Vehicle Code (CVC) contains
statutes adopted by the California Legislature relating to the operation, ownership, and
registration of vehicles in California, and changes to it are made through state
legislation. Caltrans publishes and maintains technical documents used to implement the
Vehicle Code. These include the California Manual for Setting Speed and the California
Manual on Uniform Traffic Control Devices (CA MUTCD). When local agencies set
speed limits, they must follow specific speed-procedures established by Caltrans in
these documents. At a high level, the procedures involve justifying and documenting the
chosen speed limit using an engineering and traffic survey. Engineering and traffic
surveys are discussed in further detail in Section 3.4.
In addition to roadways under the jurisdiction of Caltrans or local agencies, some roads
are overseen by tribal governments, National Parks, and private entities, who are
advised (but not mandated) to follow the CA MUTCD setting speeds.
3.2. Types of Speed Limits
California state law establishes speed limits on all roads in the state according to the
CVC. Speed limits defined by state law are called statutory limits. There are different
statutory limits depending upon the type of road being limited—such as city streets,
county roads, or state highways—and on the zone being limited, such as school zones,
business districts, and residential areas. Certain road types and zones have default
speed limits that are in effect even if no speed limit sign is posted. Codified in the CVC,
these default speed limits are called prima facie speed limits.
30 NHTSA, Countermeasures that Work, 3-8.
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Exhibit 3-1 summarizes the common types of speed limits that pertain to this report.
Exhibit 3-1 – Common Types of Speed Limits
Type Definition
Statutory Statutory speed limits are established by
the State legislature. They are enforceable
by law even if the speed limit sign is not
posted.
Prima Facie Prima facie speed limits are a type of
statutory speed limit that apply in
designated special areas or zones,
including school zones, business districts,
and residential areas. They are enforceable
by law even if the speed limit sign is not
posted.
Posted Posted speed limits can be the same as
Statutory speed limits, or they can be
different limits established by a local
authority on the basis of an engineering and
traffic survey. They must be posted in order
to be enforceable.
Absolute Absolute speed limits are statutory speed
limits. They designate an upper limit
beyond which any speed is illegal.
3.3. Establishing and Deviating from Speed Limits
While the CVC establishes speed limits for the state, it also allows local agencies to
establish specific speed limits for streets within their boundaries. When agencies want to
deviate from the statutory limits by either raising or lowering them, they adjust these
limits according to procedures and parameters established by Caltrans.
Exhibit 3-2 depicts California’s statutory speed limits and the amount that agencies are
permitted to adjust them. Crucially, in order to adjust speed limits, agencies must follow
legally-mandated procedures which usually entail conducting engineering and traffic
surveys, which are discussed in Section 3.4.
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Exhibit 3-2 – Speed Limits and Adjustment Authority on Road Types and Zones
Example Road Types
Speed
Limit
(MPH)
Adjustment Authority
Highways 65 Below 65
Freeways 65 70**
Two-lane
undivided
roadways
55 Below and over 55
Uncontrolled
railway
crossing*
15 None
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Example Road Types
Speed
Limit
(MPH)
Adjustment
Authority
Uncontrolled
intersection* 15 None
Alley* 15 None
Example Road Zones
Speed
Limit
(MPH)
Adjustment
Authority
Business
districts
without other
posted speed
limits*#
25 15 or 20
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Example Road Zones
Speed
Limit
(MPH)
Adjustment
Authority
Residential
districts
without other
posted speed
limits*#
25 15 or 20
Example Road Zones
Speed
Limit
(MPH)
Local Adjustment
Authority
School
zones* 25 15 or 20
Areas
immediately
around senior
centers*#
25 15 or 20
*These speed limits are called prima facie limits and they do not need to be physically posted (via a sign)
in order to be enforceable.
# Non-State-highway only
**Raising speed limits on State freeways to 70 MPH can be accomplished without an E&TS, based on
geometric criteria.
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Image Sources:
1. Highways
https://www.sustainablehighways.dot.gov/FHWA_Sustainability_Activities_June2014.aspx
2. Freeways
Caltrans photo database
3. Two-lane undivided roadway
http://www.gribblenation.org/2017/06/california-state-route-89-lassen.html
4. Uncontrolled railway crossing
https://en.wikipedia.org/wiki/File:Railroad_Junction2004_x.JPG
5. Uncontrolled intersection
https://safety.fhwa.dot.gov/intersection/other_topics/fhwasa08008/ue4_stop_bar.pdf
6. Alley
https://www.fhwa.dot.gov/publications/publicroads/10mayjun/05.cfm
7. Business districts
https://safety.fhwa.dot.gov/road_diets/guidance/info_guide/ch3.cfm
8. Residential districts
https://safety.fhwa.dot.gov/uslimits/documents/appendix-l-user-guide.pdf
9. School zones
https://www.kashlawpc.com/school-zone-safety-things-to-keep-in-mind-when-driving-through/
10. Senior centers
https://www.cityofnapa.org/Facilities/Facility/Details/Senior-Activity-Center-18
3.4. Engineering and Traffic Surveys – An Overview
Transportation agencies are not permitted to adjust speed limits on their streets at their
own discretion. Specific rules and procedures established by the state must be followed
in order to establish a new speed limit. The most important of these rules is the
requirement to conduct an engineering and traffic survey, also known as speed surveys
or traffic surveys. Traffic surveys must be completed for the posted speed limit to be
enforceable. As Caltrans notes in its California Manual for Setting Speed Limits, “the
setting of speed limits requires a rational and defensible procedure to maintain the
confidence of the public and legal systems.”31 The survey procedures encourage
agencies to follow a structured, methodologically sound approach that will result in a
reasonable speed limit.
Engineering and traffic surveys are the basis for the “engineering approach” to setting
speed limits, which is the most commonly used approach to setting speed limits in the
U.S. The approach follows a two-step process in which an engineer measures the 85th
percentile speed of vehicles and subsequently adjusts it based on a variety of factors to
arrive at a speed limit. While there is no universal process for conducting these surveys,
the FHWA provides guidance related to the process and most states have also
developed their own procedures.
Section 627 of the CVC defines engineering and traffic surveys. The detailed procedures
for conducting these surveys in California are described in the California Manual for
Setting Speed Limits. Exhibit 3-3 visualizes the main procedural steps at a high level.
31 Caltrans, 2014 California Manual for Setting Speed Limits, 13.
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Exhibit 3-3 – Conducting an Engineering and Traffic Survey: Main Components
In Step 4, traffic engineers are allowed to “consider other factors” in addition to the 85th
percentile speed of vehicles. The California Manual for Setting Speed Limits and the
CVC specifically identifies the factors listed in Exhibit 3-4.
Exhibit 3-4 – Other Factors that Impact Establishing Speed Limits
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The premise of Step 4, in which engineers may consider other factors including “conditions
not readily apparent to the driver,” is that it enables agencies to consider unique local
conditions when determining deviations to the 85th percentile speed. Some cities have also
been granted special provisions in the CVC that allow them to consider additional factors.
For example, in 2019 four southern California cities were legally authorized to consider
equestrian safety when conducting an engineering and traffic survey on designated streets
due to the unique circumstances of certain areas with equestrian trails.32
According to current law, a traffic survey is valid for 5 years, upon which it must be renewed.
However, under certain conditions, traffic surveys may be extended to 7 or 10 years.33
3.5. Adjusting Speed Limits from the 85th Percentile Speed
Though agencies can adjust the 85th percentile base speed limit, the adjustments
themselves are limited. In order for posted speed limits to be enforceable by law
enforcement and the court system, agencies can only deviate so much from the speed
limits established by the State.
According to the California Manual for Setting Speed Limits, speed limits are to be
posted at the nearest 5 mph increment of the 85th percentile speed. For example, if the
85th percentile speed was taken to be 33 mph, then the speed limit would be established
at 35 mph because it's the closest 5 mph increment to the 33 mph.
Under some circumstances, practitioners can deviate from the nearest 5 mph increment
when posting the speed limit. Specifically, the posted speed limit may be reduced by 5
mph from the nearest 5 mph increment of the 85th percentile speed. The following two
scenarios, drawn from the 2014 California Manual for Setting Speed Limits, explain the
application of the 5 mph reduction.
Scenario 1 graphically depicts the technical rounding process when the nearest 5 mph
increment is greater than the 85th percentile speed. In this scenario, the final speed limit
differs from the 85th percentile speed by only 3 mph.
Scenario 1: Getting from 38 mph to 35 mph
In Scenario 1 the final difference between the speed limit and the 85th percentile speed
is only 3 mph. However, the rounding process can produce greater differences.
32 California Vehicle Code (CVC) 22353.
33 CVC 40802.
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Scenario 2 demonstrates how an 85th percentile speed of 37 mph can result in a
30 mph speed limit – with a total deviation of 7 mph. This example describes when the
nearest 5 mph of the 85th percentile is less than the 85th percentile speed.
Scenario 2: Getting from 37 mph to 30 mph
In Scenario 2, the rounding process results in a speed limit (30 mph) that is 7 mph lower
from the 85th percentile speed (37 mph). Thus, 7 mph is the maximum amount that a
speed limit can be reduced from the 85th percentile speed.
Further, the speed limit can be posted at the 5 mph increment below the 85th percentile
even if mathematical rounding would require the speed limit to be posted above the 85th
percentile. If this option is used, the 5 mph reduction cannot be applied. For example, if the
85th percentile is 34 mph, the speed limit can be posted at 30 mph instead of the closest
5mph increment which is 35 mph. However, the 30 mph cannot be rounded further.
As these scenarios and examples demonstrate, the cornerstone of establishing speed
limits entails determining the 85th percentile speed via an engineering and traffic survey
and then adjusting it through a rounding process. While adjustments are permitted, the
85th percentile speed of motor vehicles is the most prominent factor in determining a
speed limit. As Caltrans notes, “speed limits set by E&TS are normally set near the 85th
percentile speed.”34 Similarly, the Federal Highway Administration notes that “the typical
procedure is to set the speed limit at or near the 85th percentile speed.”35
There are several scenarios in which it is not necessary for agencies to conduct traffic
surveys in order to post a lower speed limit. For example, in 25-mph prima facie school
zones, agencies have the option to lower the speed limit from to 20 mph or 15 mph
without conducting a traffic survey if certain criteria are met. Agencies may opt to either
conduct a traffic survey to support the lower limit, or they may pass a local ordinance
provided that the roadway design meets certain conditions stipulated in the CVC.
Despite this scenario, establishing speed limits using the 85th percentile as part of the
engineering and traffic survey process remains the most common way to establish
speed limits on California’s roadways.
34 Caltrans, California Manual on Setting Speed Limits, 14.
35 FHWA, Methods and Practices for Setting Speed Limits, 12.
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4.0 The 85th Percentile Speed Methodology – An
Analysis
This section provides a detailed analysis of the 85th percentile speed methodology,
including its history, evolution, and limitations; its usage in urban and rural settings; and
its relationship to local bicycle and pedestrian plans.
4.1. History, Evolution, and Limitations of the Idea
UC ITS researchers traced the origins of the 85th percentile concept to influential studies
in the mid-20th-century, but noted that these studies supported the conventional wisdom
at the time and were “widely accepted with little scrutiny.”36 Over time, the 85th percentile
speed came to be associated with a collection of qualitative concepts “deeply rooted in
government and law,”37 which are depicted in Exhibit 4-1. Today, the modern rationale
for the 85th percentile speed remains codified in traffic manuals, including the national
Manual on Uniform Traffic Control Devices, as well as California’s manual. The
California Manual for Setting Speed Limits maintains that “speed limits established on
the basis of the 85th percentile conform to the consensus of motorists of the reasonable
and prudent speed,”38 a practice that UC ITS refers to a crowdsourcing speed limit. Most
other countries, including Europe and Australia, do not use the 85th percentile speed to
set speed limits.
Exhibit 4-1 – The 85th Percentile Methodology: Fundamental Concepts
Key Concepts
• The majority of drivers will
naturally drive at safe,
reasonable speeds.
• Speed limits are safest when they
conform to the speed driven by
most drivers.
• The norms of a reasonable
person should be considered
legal.
• Uniform vehicle speeds increase
safety and reduce the risks for
crashes.
These concepts are coming under increasing scrutiny in response to rising traffic
fatalities. The 2017 NTSB Safety Study found that there is no strong evidence that
traveling at the 85th percentile speed results in safer outcomes and recommended that
the FHWA “remove the guidance that speed limits in speed zones should be within
5 mph of the 85th percentile speed.”39 UC ITS similarly analyzed the limitations of the
85th percentile methodology and concluded “after eight decades, vehicles are different,
our aspirations for the uses of streets are different, and our safety goals are more
ambitious.”40
36 UC ITS, Research Synthesis, 39.
37 FHWA, Methods and Practices for Setting Speed Limits, 14.
38 Caltrans, California Manual for Setting Speed Limits, 40.
39 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 54-57.
40 UC ITS, Research Synthesis, 40.
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Exhibit 4-2 summarizes the major limitations of the 85th percentile methodology
according to Task Force and Advisory Group members, the UC ITS research synthesis,
and leading national research, including studies issued by the NTSB and FHWA.
Exhibit 4-2 – The 85th Percentile Methodology: Major Limitations
Major Limitations
• Not supported by scientific
research
• Privileges driver behavior
• Based on a set of historical
assumptions
• Does not require consideration
of other road users such as
pedestrians and bicyclists
• Same methodology applied to
different roadway types
• Assumes drivers will choose
reasonable and prudent speeds
• Can lead to speed creep
Research results and the majority of Task Force and Advisory Group members support
the fact that lowering speed limits can produce meaningful safety improvements.
However, a minority Task Force perspective maintains that the only way to improve
roadway safety is through engineering and design countermeasures, and that
policymakers should not be overly focused on reducing vehicle operating speeds by
lowering speed limits. Moreover, there are risks associated with lowering speed limits
too far, as the National Cooperative Highway Research Program Project notes:
“artificially low speed limits can lead to poor compliance as well as large variations in
speed within the traffic stream. Increased speed variance can also create more conflicts
and passing maneuvers.”41
4.2. Using the 85th Percentile in Urban and Rural Settings
The 85th percentile methodology was established based on research primarily conducted
on rural roads. Rural roads are generally long stretches of uninterrupted roadway, while
urban areas are generally characterized by frequent interactions between cars and
vulnerable users of the roadway, including pedestrians and bicyclists.
Calculating the 85th percentile speed via engineering and traffic surveys is the same
regardless of roadway type. Given the differences between urban and rural settings,
applying the same methodology to different road types creates specific limitations, which
are discussed below.
4.2.1. Limitations of the 85th Percentile for Highways in Rural Settings
One of the primary limitations of using the 85th percentile in rural highway settings is the
cyclical phenomenon of speed creep. As recent research has indicated, raising speed
limits to match the 85th percentile speed of vehicles leads to higher operating speeds,
which can then contribute to a higher 85th percentile speed.42 Research has shown that
over time, vehicle operating speeds continue to increase even if the road and vehicle
41 National Cooperative Highway Research Program Project 3-67, Expert System for Recommending
Speed Limits in Speed Zones (2006), 1.
42 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, x.
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conditions remain the same, demonstrating that the posted speed limit has the most
impact on a driver’s travel speed.43
4.2.2. Limitations of the 85th Percentile for Local Streets in Urban Settings
On local streets in urban environments, speed creep is also a limitation associated with
the 85th percentile approach. Studies have demonstrated that “spatial” speed creep on
local roads can be caused by high speeds on connecting highways. Higher speed limits
on highways can thus have a “carry-over” effect on local roads.
Additionally, many limitations of the 85th percentile approach specific to local streets are
behavioral. These behavioral limitations expose the difficulties associated with basing
speed limits on driver’s habits. Driver behavior lies at the root of the 85th percentile
methodology, which assumes that most drivers will naturally choose to drive at a safe
and reasonable speed. Yet UC ITS researchers contend that drivers tend to
underestimate their speed by 10-30% and that drivers have “limited capacity” to choose
a safe speed.44 When drivers exceed the posted speed limit, one of the key reasons is
their belief that excess speed does not threaten safety. Additionally, poor weather
conditions and the lack of strong visual cues on local roads (such as guardrails or trees)
can further cause drivers to underestimate their speeds.
These research results indicate that drivers are not good at “naturally” selecting safe
speeds and suggests that it is not prudent to use driving habits as a basis for
establishing speed limits. Ultimately, “the conjecture that safe speed limits should be
determined based on the actual driving habits of drivers cannot be used to establish safe
travel speeds on local streets.”45
4.3. Effect of Bicycle and Pedestrian Plans on the 85th Percentile
Increasing numbers of California cities and counties are creating bicycle and pedestrian
transportation plans. These local planning documents, which are defined in the
California Transportation Commission’s Active Transportation Program Guidelines, as
the first step to either initiate or continue with programs, policies, and projects that
provide safe and efficient travel modes for bicyclists and pedestrians. In 2017, Caltrans
released the first-ever statewide bicycle and pedestrian plan called Toward an Active
California which outlines the policies and measures that the State and local governments
can take to increase bicycling and walking.
However, local government bicycle and pedestrian plans do not impact posted speed
limits, which is primarily determined by the 85th percentile speed of motor vehicles. When
calculating the 85th percentile speed of vehicles, there is no existing mandate to consider
where future bicycle and pedestrian facilities are planned or in progress.
43 UC ITS, Research Synthesis, 46.
44 Ibid., 46-47.
45 Ibid., 47.
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However, if a city implements bicycle and pedestrian elements from its plan that changes
roadway infrastructure, the project might affect the 85th percentile speed of vehicles. For
instance, if a local jurisdiction implemented certain traffic calming interventions such as
speed bumps, it could cause drivers to slow down which then impacts the 85th percentile
speed of vehicles. Studies in Denmark and the United States have shown that the
installation of a single speed bump reduced average speeds by 2.7 to 3.4 mph.46
46 UC ITS, Research Synthesis, 57.
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5.0 Alternatives to the 85th Percentile – Local, State,
National, and International Trends in Setting
Speed Limits
This section describes alternatives to the 85th percentile methodology to setting speed
limits. It explores recent changes in setting speeds limits at the local, state, national, and
international levels.
5.1. Summary
AB 2363 mandates that this report include “existing reports and analyses on calculating
the 85th percentile at the local, state, national, and international levels.” While data
collection methods and procedures may differ slightly, the 85th percentile speed is a well-
documented methodology that does not significantly vary in its calculation at the local,
state, national, and international levels. However, there are entirely different approaches
to establishing posted speed limits that do not take the 85th percentile speed into account.
Exhibit 5-1 provides a summary of the different approaches to setting speed limits.
Exhibit 5-1 – Approaches to Setting Speed Limits47
Approach Description Jurisdictions
Engineering (or
Operating)
A two-set process where a base
speed limit is set according to the
85th percentile speed and adjusted
slightly according to road and
traffic conditions, crash history,
and other factors.
United States
Safe System Speed limits are set according to
the crash types that are likely to
occur, the impact forces that
result, and the tolerance of the
human body to withstand these
forces.
Sweden, Netherlands,
Australia
Expert System Speed limits are set by a computer
program that uses knowledge and
inference procedures that simulate
the judgement and behavior of
speed limit experts. In the U.S.,
USLIMITS2 is a web-based expert
speed zoning software advisor
adapted from similar expert
systems used in Australia.
United States, Australia
47 FHWA, Methods and Practices for Setting Speed Limits, 24. (Adapted).
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Approach Description Jurisdictions
Engineering (or
Road-Risk)
Speed limit is determined by the
risks associated with the design of
the road. The speed limit is based
on the function of the road and/or
the adjacent land use and then
adjusted based on road and traffic
conditions and crash history.
Canada, New Zealand
Optimization /
Optimal
Setting speed limits to minimize
the total societal costs of transport.
Travel time, vehicle operating
costs, road crashes, traffic noise,
and air pollution are considered in
the determination of optimal speed
limits.
Conceptual approach
that has not been
adopted by any road
authority
5.2. International Trends
Many countries including the Netherlands, Sweden, and Australia approach setting
speed limits from a different conceptual framework. Instead of establishing speed limits
based on driver operating behavior, many countries begin with the premise that the
human body is vulnerable and unlikely to survive impact speeds more than 40 mph.
According to UC ITS, based on this understanding, other countries minimize the severity
of road traffic crashes through programs such as Vision Zero, Sustainable Safety, and
Safe Systems.48 Although these programs have different names in different countries,
they share common principles and strategies with an emphasis on safety. The 2017
NTSB Safety Study presents a summary description of the safe systems approach:
The safe system approach to speed limits differs from the traditional view that
drivers choose reasonable and safe speeds. In the safe system approach, speed
limits are set according to the likely crash types, the resulting impact forces, and
the human body’s ability to withstand these forces. […] It allows for human errors
(that is, accepting humans will make mistakes) and acknowledges that humans
are physically vulnerable (that is, physical tolerance to impact is limited).
Therefore, in this approach, speed limits are set to minimize death and serious
injury as a consequence of a crash.”49
Sections 5.2.1, 5.2.2, and 5.2.3 present international case studies of this different
approach to establishing speed limits. These case studies are adapted from the UC ITS
Research Synthesis.
5.2.1 Netherlands
The Netherlands adopted “Sustainable Safety” as a vision in 1992. This paradigm shift
used safety as a design principle for the road traffic system and emphasized how to
prevent human errors to the extent possible and how to minimize the severity of a crash.
Specifically, the Netherlands:
48 UC ITS, Research Synthesis, 49.
49 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 28.
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• Expanded 30 km/h (18.6 mph) zones from 15.5 percent of their urban residential
streets to 54.5 percent by adopting a “low-cost” approach that phased the
introduction of the lower speed limits. In the short-term, communities posted the
new speed limits with some support of traffic calming devices with the goal to
further transform the area through additional engineering features.
• Introduced 60 km/h (37.3 mph) zones, down from 80 km/h (49.7 mph), for rural
access roads that met specific criteria warranting reduced speeds to improve
safety for vulnerable users and/or located in transition zones.
5.2.2 Sweden
Sweden adopted the Vision Zero road safety philosophy in 1997 with the long-term goal
that no person should be killed or seriously injured in road traffic. Their system relies on
two principles: 1) human life and health are the top priority when designing roads; and
2) road traffic safety is a shared responsibility between all road users and system
designers. Under the safe system approach in Sweden, speed limits were reduced to
prioritize the highest levels of safety.
Sweden designed their road system based on what the human body can endure in both
a vehicle-vehicle and vehicle-unprotected user (e.g., pedestrian, bicyclist) crash
scenario. As part of the safe system approach, Sweden introduced median barriers to
prevent head-on crashes, safer roadsides, traffic calming, roundabouts, separation, and
reduced speed limits.
Sweden made a distinction between urban and rural roads, resulting in the
implementation of parallel efforts. They reviewed their national rural road network and
established guidelines for each road type classification balancing traffic safety,
environment, and mobility and accounting for regional differences. This resulted in a
statistically significant reduction in the mean operating speed of passenger cars. For
speeds in urban areas, Sweden established guidelines that consider the city’s character,
accessibility, security, traffic safety, and health and environment. This resulted in a mean
operating speed decrease of 2-3 km/h (1.2-1.9 mph).
5.2.3 Australia
The New South Wales (NSW) Roads and Traffic Authority adopted the Safe Systems
approach to develop and implement its road safety programs, with lower speeds and
speed limits as essential components. The Safe Systems approach was adopted in 2004
and is guided by the vision that no person should be killed or seriously injured on
Australia’s roads.
Australia’s approaches include safer people, roads, vehicles, and speeds collectively
and reinforces that the determination of safe speed limits must account for a myriad of
factors, including hazards, the road environment, and the movement and presence of
different road users. It suggests that those who design, operate, and manage the road
system are responsible for the safety of the network.
NSW uses a 50 km/h (31 mph) default urban speed limit, increasing to 60 km/h
(37.3 mph) on major arterial roads. A speed limit of 70 km/h (43.5 mph) and 80 km/h
(49.7 mph) may be applied but requires restricted abutting access and low to no
pedestrian activity. Higher speeds are restricted to motorways and top out at 110 km/h
(68.4 mph). Shared zones are restricted to 10 km/h (6.2 mph) while school zones and
other areas with high pedestrian traffic or local traffic are restricted to 40 km/h (24.9 mph).
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Work zones also have reduced speed limits. NSW uses variable speed limits which adapt
to changes in traffic management and incident responses, weather, and roadwork.
5.3. Recent National Trends
In the U.S. the safe systems approach to traffic safety is gaining momentum, influenced
by international best practices and by recent important safety studies. In 2017, the NTSB
safety study found that the safe system approach to setting speed limits in urban areas
represented an improvement over conventional approaches because it considers the
vulnerability of all road users.50 The study also advised the Federal Highway
Administration “remove the guidance that speed limits in speed zones should be within
5 mph of the 85th percentile speed.”51
The growing popularity of the safe systems approach is also reflected by the growth of
Vision Zero, an initiative that strives to eliminate all traffic fatalities and severe injuries by
targeting local jurisdictions and encouraging them to adopt speed-management policies
and roadway design practices. As of early 2019, more than 40 U.S. cities – including
Sacramento, San Francisco, and Los Angeles – have adopted policies from this initiative
and are designated as Vision Zero Cities.52
Reflecting these trends, states across the U.S., including Oregon, Washington, and New
York are adopting speed-limit-setting laws that grant local agencies more flexibility to
establish lower speed limits. Localities, in turn, are leveraging this ability to reduce speed
limits and make safety improvements.
Sections 5.3.1, 5.3.2, 5.3.3, and 5.3.4 of this report present U.S. case studies that reflects
this trend. These case studies are adapted from the UC ITS Research Synthesis.
5.3.1. Oregon
In 2017 the Oregon legislature gave the City of Portland the authority to lower its
residential speed limits from 25 mph to 20 mph. The Legislature extended this authority
to all Oregon cities in 2019 via Senate Bill 558.
All of Portland's 3,000 miles of residential streets now have a maximum speed of
20 mph. Portland also has permission to use an “alternative method”53 for non-arterial
streets that references the 85th percentile speeds but places greater emphasis on
vulnerable users and the risk of a future crash. Locations where this alternative method
is used will require an evaluation report after a two-year trial period focusing on the
changes in the number of injury and fatal crashes. This methodology was approved in
2016 and the experimental period was extended to four-years to account for crash data
report lag time.
50 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 54.
51 Ibid., 57
52 Vision Zero Network, Vision Zero Cities (2019).
53 Oregon Department of Transportation, Article 595455 (2016).
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5.3.2. Washington
In 2013 the Washington Legislature passed a law allowing municipalities to establish a
maximum speed limit of 20 mph in a residential or business district. Enabled by this
legislation, in 2016 Seattle City Council lowered the speed limit on residential streets
from 25 mph to 20 mph and the lowered the default speed limit from 30 mph to 25 mph
on arterials (larger streets that are primarily in downtown and nearby neighborhoods).
Additionally, the Legislature passed a law amending the State’s Manual on Uniform
Traffic Control Devices (MUTCD) that provides local jurisdictions with considerations
about what requirements they need to meet in order to revise speed limits.
The Seattle Department of Transportation (SDOT) compiled a data-based justification in
support of the lower speed limits. SDOT made the case that the design of the road the
city’s Vision Zero commitment, and recent mode shift away from driving and toward
walking, biking, and taking transit all signaled a need for lower, safer speed limits. SDOT
also included speed and safety data from all of their recent Vision Zero pilot projects.
Since the law passed, SDOT has built on the momentum of reducing speed limits across
the city to leverage existing state-level authority to reduce speed limits on three high-
crash corridors using a context-sensitive engineering study. They are also leveraging
both of these tools to reduce speed limits at a neighborhood scale in particular zones.
5.3.3. New York
In 2014 the New York State Legislature allowed New York City to reduce the citywide
default speed limit from 30 mph to 25 mph.
In addition to lowering citywide speed limits to 25 mph, the city also created numerous
Neighborhood Slow Zones across the five boroughs in response to applications from
communities. These zones typically include 20 mph on-street markings, signs, speed
humps, and other traffic calming treatments and are typically small residential areas with
low traffic volumes and minimal through traffic. According to the city, the ultimate goal of
the Neighborhood Slow Zone program is to lower the incidence and severity of crashes.
Slow Zones also seek to enhance quality of life by reducing cut-through traffic and traffic
noise in residential neighborhoods.54
The State Legislature also granted permission to establish an automated speed
enforcement program involving cameras located in school zones. In 2019, having
lowered speeding by over 60 percent in camera locations, the City obtained new
authority to expand this program from 140 to 750 zones.
5.3.4. Massachusetts
Massachusetts state law allows local jurisdictions to adopt a 25 mph default citywide
speed limit on municipal roads in “thickly settled” areas. They may also establish 20 mph
safety zones based on criteria of their choosing. Communities that decide to reduce the
statutory speed limit to 25 mph are required to “opt in” to the program by notifying the
state Department of Transportation. As of September 2019, 42 have opted in, including
Cambridge and Boston.55
54 New York City Department of Transportation, Neighborhood Slow Zones (2019).
55 Massachusetts Department of Transportation, Speed limits in thickly settled or business districts
(2019).
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In 2016, Cambridge lowered speed limits to 25 mph citywide and began implementing
20 mph safety zones later that same year. In 2017, Boston reduced the default speed
limit from 30 mph to 25 mph. A before-and-after by the Insurance Institute of Highway
Safety found that the estimated odds of a vehicle exceeding 35 mph fell 29.3%, the
estimated odds of a vehicle exceeding 30 mph fell 8.5%, and the estimated odds of a
vehicle exceeding 25 mph fell 2.9%.56 The study concluded that updated state laws that
allow municipalities to set lower speed limits on urban streets without requiring costly
engineering studies can provide flexibility to municipalities to set speed limits that are
safe for all road users.
5.4. Conclusion: Shifting Paradigms
At all levels – international, national, state, and local – establishing speed limits based
on safety is increasingly widespread. As more agencies emphasize the safety of all road
users as fundamental to establishing speed limits, the traditional 85th percentile
approach and its inherent privileging of vehicle throughput and driver behavior is giving
way to more multi-faceted, context-sensitive, safety-based approaches. However, as the
NTSB safety study notes, “although local officials may wish to incorporate the safe
system approach by proposing speed zones with lower limits in urban areas with
vulnerable road users, they may be unable to do so because state transportation
departments require engineering studies that are driven by the 85th percentile speed.”57
In the U.S., states are passing legislation that grants local agencies more flexibility to
establish lower speed limits, which local jurisdictions are using to lower speed limits to
increase safety. Ultimately, increased safety outcomes require cooperation and
coordination at both the state and local levels.
56 Insurance Institute for Highway Safety, Lowering the Speed Limit from 30 to 25 mph in Boston: Effects
on Vehicle Speeds (2018), cited in UC ITS, Research Synthesis, 54-55.
57 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 29.
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6.0 Engineering and Designing for Safety – Roads and
Vehicles
This section explores roadway engineering and design countermeasures and emerging
vehicle technologies to increase safety.
6.1. Engineering Countermeasures
A road’s posted speed limit is not the only factor that drivers consider when choosing
how fast to drive. The physical design of a roadway (such as lane numbers and width,
the presence of intersections, roundabouts, and the surrounding landscape) also
influences a driver’s velocity and is an important component in speed management. As a
recent study noted, “our preferences and judgments of appropriate speed are strongly
influenced by setting and perspective.”58 The speed at which we choose to operate our
vehicles is known as operating speed. A driver’s operating speed can be influenced by
many complex factors, but generally speaking, motorists will drive faster on wide,
uncongested roads. They will drive slower on narrow roads with sight markers (such as
trees) that provide subconscious feedback on their speeds.
Engineering countermeasures have been identified as one of three types of
countermeasures (the others are education and enforcement) that can mitigate a
speeding-related safety problem.59 Engineering countermeasures are predicated on the
fact that roads can be designed to increase or decrease a driver’s operating speed. This
design speed is an important component of overall speed management and as defined
by the FHWA “is the selected speed used to determine the various geometric design
features of the roadway.”60
Traffic engineers use a variety of technical terms to discuss changing roadway
infrastructure to force drivers to change their behavior. These terms include engineering
countermeasures, traffic-calming devices, self-enforcing roadways, geometric design,
roadway geometry, physical measures, and roadway design features.
While these terms are not synonymous, they are generally used when discussing “any
intentional, long-term alteration to the roadway or its environment that causes changes
in motorists’ driving behavior.”61 According to the FHWA’s Traffic Calming ePrimer, while
the exact wording may differ, “the essence remains that traffic calming reduces
automobile speeds or volumes, mainly through the use of physical measures, to improve
the quality of life in both residential and commercial areas and increase the safety and
comfort of walking and bicycling.”62
58 FHWA, Speed Concepts: Informational Guide, 7
59 NHTSA, Speed Enforcement Camera Systems Operational Guidelines (2008), 8.
60 Ibid., 9
61 FHWA, Speed Management Countermeasures Fact Sheet (2017), 1.
62 FHWA, Traffic Calming ePrimer (2017). Module 2.1.
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Exhibit 6-1 provides images, descriptions, and costs of common engineering and design
solutions.
Exhibit 6-1 – Common Roadway Engineering Elements and FHWA Estimated Cost*
Example Description
FHWA
Estimated
Construction
Cost
Curb extensions
Curb extensions visually and
physically narrow the roadway
and increase the overall
visibility of pedestrians by
reducing the crossing distance
for pedestrians.
$8,000-$12,000
Chicanes
A chicane is a series of
alternating mid-block curb
extensions or islands that
narrow the roadway and
require vehicles to follow a
curving, S-shaped path.
$8,000-$10,000
Chokers
Chokers are types of curb
extensions that narrow a street
by widening the sidewalks or
planting strips, effectively
creating a pinch-point along
the street.
$10,000-
$25,000
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Example Description
FHWA
Estimated
Construction
Cost
Median islands
Median refuge islands are
protected spaces placed in the
center of the street to facilitate
bicycle and pedestrian
crossings.
$15,000-
$55,000
Raised crosswalks
Raised crosswalks bring the
level of the roadway to that of
the sidewalk, forcing vehicles
to slow before passing over
the crosswalk and providing a
level pedestrian path of travel
from curb to curb.
$4,000-$8,000
Roundabouts
A roundabout is a type of
circular intersection that is
different than a traffic circle.
Traffic travels
counterclockwise around
center island and vehicles
entering the roundabout must
yield to enter.
$150,000-
$2 million
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Example Description
FHWA
Estimated
Construction
Cost
Speed humps/speed table
Speed humps and tables are
devices that encourage people
driving to slow down. Speed
humps and tables are raised
areas that extend across the
street. A speed hump is
rounded whereas a speed
table has a flat top to
accommodate a car’s entire
base.
Speed hump:
$2,000-$4,000
Speed table:
$2,500-$8,000
Traffic circles
Traffic circles guide vehicles
through an intersection in one
direction around a central
island. They are usually
installed at
intersections of neighborhood
streets.
$10,000-
$25,000
*Sources: U.S. Department of Transportation Federal Highway Administration Traffic Calming ePrimer
(https://safety.fhwa.dot.gov/speedmgt/traffic_calm.cfm#eprimer); National Association of Transportation
Officials Urban Street Design Guide (https://nacto.org/publication/urban-street-design-guide/)
Image Sources:
1. Curb Extensions
https://safety.fhwa.dot.gov/speedmgt/ePrimer_modules/module3.cfm
2. Chicanes
https://safety.fhwa.dot.gov/speedmgt/ePrimer_modules/module3.cfm
3. Chokers
https://safety.fhwa.dot.gov/speedmgt/ePrimer_modules/module3pt2.cfm
4. Median Islands
https://www.fhwa.dot.gov/publications/publicroads/11marapr/03.cfm
5. Raised Crosswalks
https://safety.fhwa.dot.gov/ped_bike/step/docs/TechSheet_RaisedCW_508compliant.pdf
6. Roundabouts
https://safety.fhwa.dot.gov/hsip/hrrr/manual/sec43.cfm
7. Speed humps/speed table
https://safety.fhwa.dot.gov/local_rural/training/fhwasa010413spmgmt/
8. Traffic circles
https://safety.fhwa.dot.gov/speedmgt/ePrimer_modules/module3.cfm
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Within the context of reducing speed and calming traffic, engineering countermeasures
are commonly used to slow down traffic, reduce overall traffic volume, reduce cut-
through traffic, provide more space for bicyclists and pedestrians, and increase their
visibility to drivers. Engineering and design countermeasures can offer a more holistic
approach instead of treating streets solely as a conduit for vehicles and balance traffic
on streets with other needs of the community. As the exhibit depicts, costs can vary
widely depending on the type of solution.
Many studies find that engineering changes are the most effective interventions at
reducing pedestrian injury and fatality rates.63 UC ITS documented the safety
improvements associated with multiple engineering solutions. Studies in Denmark and
the United States, for instance, have shown that the installation of a single speed bump
reduced average vehicle speeds by 2.7 to 3.4 mph, and another American study found
that installing multiple speed bumps in succession can reduce average vehicle speeds
by 8 to 12 mph in some areas.64 Horizontal deflections such as chicanes and lane shifts
have also been demonstrated to reduce vehicle speeds. Chicanes have been found to
reduce average speed by 1.3 to 3.2 mph.65 Roundabouts have also been found to
reduce the speed of vehicles at intersections and have consistently shown to reduce all
crashes in all intersection contexts in the range of 35-76% in the United States.66
Task Force members overwhelmingly agree that changing a road’s infrastructure is the
most important factor to reduce vehicle operating speeds. When surveyed, 13 of 15
survey respondents said that design elements effectively reduce speeds. One Task
Force member noted that a local city had recently reduced the speed limit in school
zones. However, the accompanying wide streets encouraged drivers to ignore the signs
and continue driving fast; the lowered speed limit was in itself “not enough to make our
streets truly safe.”
The effect of roadway design on safety is widely accepted, and the Federal Highway
Administration recently released a national pedestrian safety action plan that focuses
significant attention on improving pedestrian safety through street redesign and
engineering-related countermeasures, as well as the policies that influence street design
choices. There are a variety of other sources for cities who wish to pursue engineering
countermeasures; these include the National Association of City Transportation Officials’
design guides, the Federal Highway Administration’s Traffic Calming ePrimer, and the
Highway Design Manual published by Caltrans.
However, there are many challenges associated with changing roadway infrastructure to
reduce operating speeds. The Caltrans Highway Design Manual does not include
standards and specifications for many types of horizontal and vertical traffic calming
devices. While large cities such as San Francisco and Los Angeles have developed their
own engineering and design guides, smaller cities do not have the resources to produce
their own standards and rely on a variety of other sources. Currently, no definitive
document exists that provides California cities and counties with comprehensive
engineering and design options to reduce vehicle operating speeds.
63 UC ITS, Research Synthesis, 57.
64 Ibid., 57.
65 Ibid., 57.
66 Ibid., 58.
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Roadway engineering solutions to reduce operating speed can widely vary in cost, and
can include complex multi-million-dollar construction projects. Changing roadway
infrastructure on a large scale can be a costly and time-consuming process that can take
years. The process involves planning, prioritizing, securing funding, designing, and
installation. According to the FHWA, “once constructed, transportation infrastructure is
enduring […] Alterations may be costly and disruptive. Since the consequences of
roadway design are significant and long-lasting, decisions should be deliberate.”67 Task
Force and Advisory Group members noted that cost and length of time as obstacles to
using engineering countermeasures to achieve safer speeds.
In addition to these obstacles, another potential barrier to lowering vehicle operating
speeds is the need to meet Level of Service (LOS) requirements. In city planning
documents, through state permitting processes, and through the environmental review
process, acceptable vehicle LOS for specific roadways is often identified and used in
order to avoid excessive traffic congestion and delay. LOS is a metric used to rate the
quality of vehicle traffic service based on performance measures like speed, travel time,
delay, and congestion. There are six levels of service ranging from "A" through "F," with
LOS "A" representing the best range of operating conditions and LOS "F" representing
the worst.
When implementing engineering countermeasures designed to reduce vehicle operating
speeds, agencies may have to consider the LOS level on a given roadway. For instance,
the City of El Centro requires that projects with a significant impact on its transportation
system and LOS criteria must mitigate the impact through physical improvements and/or
impact fees.68 In contrast, the City of Roseville notes in its general plan that the
implementation of pedestrian districts may slow cars down and reduce the level of
service. It thus exempts pedestrian districts from its LOS policy.69
Roseville’s exemption illustrates the tradeoff between safety and vehicle level of service
within the context of roadway engineering: lower speed limits reduce the probability of
crashes but also reduce vehicle levels of service. According to the National Highway
Traffic Safety Administration (NHTSA), U.S. communities that privilege levels of service
have wide roads with minimal pedestrian accommodations and “consequently, they often
experience higher crash rates for all roadway users, as both motorists and pedestrians
suffer from the less safe conditions created to achieve these higher levels of vehicle
mobility.”70
In addition to this fundamental tension, Advisory Group members indicated that roadway
funding is sometimes contingent on Level of Service-based improvements such as street
widening and capacity enhancements, which tend to increase vehicle operating speeds.
67 FHWA, Speed Concepts: Informational Guide, 33.
68 City of El Centro, El Centro General Plan Circulation Element (2004), 18.
69 City of Roseville, General Plan 2035 Circulation Element (2016), III-15.
70 NHTSA, How to Develop and Pedestrian Safety Action Plan (2009), 10.
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Exhibit 6-2 summarizes the primary barriers to the implementation of engineering
solutions designed to lower vehicle operating speed.
Exhibit 6-2 – Engineering and Design Solutions: Barriers to Implementation
Barrier Description
• Cost Roadway infrastructure can range from $2,000 to
$2 million depending on the design treatment.
• Long timeline Implementing new roadway infrastructure can take
years to plan, fund, design, and implement.
• Funding Funding for infrastructure can be difficult to obtain
and can be contingent upon certain criteria.
• Level of Service
standards
Level of Service standards stipulate acceptable
thresholds for traffic congestion and delay.
As agencies work to balance the proven effectiveness of engineering countermeasures
to reduce operating speed with their cost, length, and complexity, it is important to note
that some can be low-cost and low-intervention. These include pavement markings (e.g.,
lane narrowing), static signing (e.g., chevron signs), and dynamic signing (e.g., speed
activated speed limit signs, speed activated warning signs), For instance, research has
demonstrated that speed feedback signs, which display a vehicle’s current speed to
remind the driver to slow down, have been effective at reducing speeds by 5 mph.71
In order to identify the most effective engineering countermeasures, traffic and
transportation professionals can also employ a research-based baseline to quantify the
expected safety effectiveness of a countermeasure. One commonly method to achieve
that is using crash modification factors (CMF).
As described by UC ITS, a CMF is an estimate of the change in crashes expected after
implementation of a countermeasure. CMFs are applied to the estimated crashes without
treatment to compute the estimated crashes with treatment. The FHWA CMF Clearinghouse
is a web-based database of CMFs along with supporting documentation to help users identify
the most appropriate countermeasure for their safety needs. The CMF Clearinghouse
contains more than 3,000 CMFs for various design and operational features.72
In a preliminary effort to identify the most pertinent crash types for California, UC ITS
generated descriptive crash statistics for California based on analysis of data from the
Statewide Integrated Traffic Records System (SWITRS) for the years 2014-2018.
Results indicated that large number of fatal and severe crashes are head-on or
overturned vehicle crash types. These specific crash types can be alleviated by road
design features that provide better road side barriers and better separation from head on
traffic. The CMF clearinghouse provides a list of quality CMF’s that are expected to
reduce such crashes.
71 FHWA, Speed Management Countermeasures Fact Sheet.
72 UC ITS, Research Synthesis, 64.
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Additionally, UC ITS identifies certain key resources (maintained by NHTSA, FHWA, and
CDC) that can support practitioners in identifying a set of road design improvements to
reduce crashes of all modes. Crash modification factors are listed for many of the
countermeasures, and such factors can be used to calculate cost-benefit estimates. The
documents demonstrate that continued application of currently available proven
countermeasures can extend the decades-long trends toward greater road safety.
6.2. Emerging Vehicle Technologies
Emerging vehicle technologies that are designed to help drivers avoid crashes are
quickly entering the motor vehicle marketplace in the U.S. These technology systems,
known as advanced driver assistance systems, rely on external sensors to gather
information about possible hazards and deploy various interventions, including collision
warnings and automated emergency braking, to help drivers avoid crashes. Many
vehicle safety and crash avoidance systems are offered to consumers as optional and
are not standard. However, adoption of these emerging technologies by consumers and
automakers is growing.
For instance, in 2016 the National Highway Traffic Safety Administration and the
Insurance Institute for Highway Safety announced the commitment of 20 major
automakers to make automatic emergency braking a standard feature on virtually all
new cars by 2022.73 Through this commitment, consumers will have access to this
technology more quickly than would be possible through the regulatory process.
Such urgency is due to the safety improvements demonstrated by these driver-assisted
technologies. Research is beginning to describe the safety benefits of various levels of
emerging technology.74 For example, the NTSB concluded that intelligent speed
adaptation (ISA) technology has been studied extensively and that it is “an effective
vehicle technology to reduce speeding.”75 ISA works by comparing a vehicle’s global
position system (GPS) to the road’s speed limit and either warning the driver or slowing
the vehicle in the case of excessive speed.
Exhibit 6-3 provides an overview of common advanced driver assistance systems
(ADAS). Some of these technologies provide warnings and rely on the driver to take
corrective action; others are designed to automatically brake or steer, taking a more
active approach.
Exhibit 6-3 – Advanced Driver Assistance Systems
Feature Acronym Description
Intelligent
speed
adaptation
ISA ISA systems compare a vehicle’s global position
system (GPS) to the road’s speed limit and either
warn the driver or slow the vehicle in the case of
excessive speed.
Blind spot
warning
BSW BSW systems detect vehicles traveling in the
vehicle’s blind spot and provide some form of warning
to the driver.
73 NHTSA, Fact Sheet: Auto Industry Commitment to IIHS and NHTSA on Automatic Emergency Braking
(2016).
74 UC ITS, Research Synthesis, 68.
75 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 45.
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Feature Acronym Description
Automatic
emergency
braking
AEB AEB systems determine the distance between the
vehicle and other vehicles/objects directly ahead and
automatically apply brakes when it senses a crash is
imminent. Many current-generation AEB systems are
also designed to detect and respond to pedestrians
and cyclists.
Forward
collision
warning
FCW FCW systems determine the distance between the
vehicle and other vehicles/objects directly ahead and
warn the driver when the system determines an
imminent threat. Many current-generation FCW
systems are also designed to detect and respond to
pedestrians and cyclists.
Lane Departure
Warning / Lane
Keeping Assist
LDW/LKA LDW and LKA systems use cameras to determine the
position of the vehicle in relation to lane markings.
LDW systems are designed to prevent crashes in
which the vehicle leaves its travel lane unintentionally.
A recent research brief on advanced driver assistance systems, sponsored by the AAA
Foundation for Traffic Safety, provided new estimates on the number of crashes, injuries, and
deaths that such systems could potentially help prevent based on 2016 U.S. crash
characteristics. The brief estimates that these technologies, if installed on all vehicles, would
have had the potential to help prevent or mitigate roughly 40% of all crashes involving
passenger vehicles, and 37% of all injuries and 29% of all fatalities that occurred in those
crashes. It concludes that “Current and future vehicle safety systems have the potential to
dramatically reduce the number of crashes, injuries and fatalities on our roadways.”76
76 AAA Foundation for Traffic Safety, Potential Reductions in Crashes, Injuries, and Deaths from Large-
Scale Deployment of Advanced Driver Assistance Systems (2018), 9.
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7.0 Speed Enforcement
This section provides an overview of speed enforcement considerations with a focus on
automated speed enforcement.
7.1. Overview of Speed Enforcement
Speed limits and speed limit enforcement are intertwined. Appropriately set speed limits
must be enforced to be optimally effective, and the purpose of enforcement strategies is
to increase compliance with traffic laws, including the legal speed limit.77 Enforcement is
one of three categories of countermeasures (in addition to engineering and education)
identified by the FHWA that can mitigate a speeding-related safety problem, as
enforcement can deter speeding and penalize violators. There are many methods to
conduct enforcement, including, regular traffic patrols, high visibility enforcement, and
automated speed enforcement. Automated speed enforcement is discussed in
Section 7.2 and high visibility enforcement is discussed in Section 7.3.
However, speed limit enforcement is only one of the duties of an officer. With competing
resource needs, law enforcement agencies must make decisions how much time to
devote to speed enforcement and how to structure an effective speed enforcement
program. The NHTSA’s Speed Enforcement Program Guidelines provides guidance for
local agencies on speed enforcement programs and notes that there is no single best
method for enforcing speeds:
Each jurisdiction needs to customize a combination of technologies and
tactical methods to enforce speeds that works best for its community. […]
Speed enforcement countermeasures need to be tailored to the particular
problems identified in the community and local circumstances. The selected
enforcement methods should be based on analysis of data on speeds and
crashes and on citizen reports.78
In California, speed limit enforcement programs face several challenges, including the
lack of adequate law enforcement staffing. Following the 2008 recession, law
enforcement agencies severely cut back their resources for traffic safety enforcement
activities. While traffic fatalities in California have continued to rise, law enforcement
staffing levels have not rebounded. The California Office of Traffic Safety (OTS) provides
some Federal funds for traffic safety enforcement, and some California jurisdictions
would not have dedicated traffic safety enforcement officials without these funds.
According to the California Vehicle Code, a speed trap is defined as a section of a
highway with a prima facie speed limit if the limit is not justified by an engineering and
traffic survey conducted within 5-10 years prior to the date of the alleged violation and if
the enforcement of the limit involves the use of radar or other electronic devices.79 In
short, if the roadway’s speed limit is not supported by a current traffic survey, the limit
cannot be enforced using lidar or radar. However, this does not apply on State-defined
local roads, which are exempt from speed trap regulations. This exemption enables
authorities to enforce speed limits on local roads without a valid traffic survey.
77 NHTSA, Countermeasures that Work, 8-36.
78 NHTSA, Speed Enforcement Program Guidelines (2008), 14-15.
79 CVC 40802.
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Local agencies on the Task Force state that they struggle to meet the State requirement
to update their engineering and traffic surveys. Posted speed limits in California are not
enforceable if the underlying traffic speed surveys have expired. To enforce posted
speed limits using lidar or radar, local agencies must update a street’s engineering and
traffic survey every 5 to 10 years. Some city representatives on the Task Force maintain
that they struggle to find the resources needed to update the traffic surveys on their
roads. Without a current traffic survey on file for a particular roadway, speeding tickets
issued using lidar or radar are not defensible in court since these conditions meet the
statutory definition of a speed trap.
According to its city documents, Los Angeles experienced a backlog of engineering and
traffic surveys in 2015. Unable to update speed surveys at the rate at which they were
expiring, the city noted that only 19% of its speed limits within its high injury networks were
able to be enforced with radar.80 (High Injury Networks are streets where high numbers of
fatal and serious crashes are concentrated.) The City Council directed the Department of
Transportation to update all eligible surveys. Based on the survey results, the City passed
an ordinance in 2018 to raise the speed limit on over 100 miles of its streets.81
This example illustrates a particular predicament that is the byproduct of current law: if
cities do not update their traffic surveys, they cannot enforce the speed limit using radar,
but if they do update their traffic surveys, speed limits are likely to rise, since speed
creep is an unintended consequence of using the 85th percentile methodology.
Despite these challenges, enforcing speed limits is an effective countermeasure to
reducing speeding and eliminating crashes, serious injuries, and fatalities on California’s
roadways. Effective enforcement is an important additional step that can be taken to
make roadways safer as part of a multifaceted approach, and it is even more effective
when combined with public education. As the FHWA notes, “traffic enforcement is most
effective when it is highly visible and publicized, to reinforce the required behavior and to
raise the expectation that failure to comply may result in legal consequences.”82
7.2. Automated Speed Enforcement
While there are many enforcement methods available to law enforcement agencies,
automated speed enforcement (ASE) harnesses technology to reduce speeding. ASE
detects speeding violations and records identifying information about the vehicle and/or
driver. Typically, radar or lidar is set to detect vehicles going above a certain speed.
Once a speed vehicle is detected by the radar system, the camera is triggered. Cameras
are either permanently fixed on poles or are mobile. The camera takes a picture of the
license plate and, depending on the program specifics, the driver. (Some programs
require drivers to be identified while others do not.) At a later time, a back-office
processor reviews and processes the violation. This processor can be a law
enforcement officer or a third-party vendor. In processing, the individual determines if a
violation occurred and matches the camera information to vehicle registration
information. Lastly, a citation is mailed to the vehicle driver or owner (depending on the
specifics of the program).
80 City of Los Angeles Department of Transportation, Enhanced Speed Enforcement and Tools to Reduce
Speeding (2015), 5.
81 City of Los Angeles Board of Transportation Commissioners, Ordinance Approval for Recommended
Speed Limit Revisions and Additions, (2018).
82 NHTSA, Countermeasures that Work, 8-36.
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All ASE systems have three basic components:
1) Speed measuring (typically using radar or its laser equivalent lidar)
2) Data processing and storage
3) Image capture
Exhibit 7-1 provides a visual high-level overview of this process.
ASE has been in use worldwide and its effects on traffic speeds and crashes has been
studied for more than two decades. ASE has proven to be an effective countermeasure
to reduce speed-related crashes and injuries.83 In its 2017 Safety Study, the NTSB
analyzed studies of ASE programs, including U.S. programs. These studies
demonstrated significant safety improvements in the forms of reduction in mean speeds,
reduction in the likelihood of speeding more than 10 mph, and reduction in the likelihood
that a crash involved a severe injury or fatality.84 In the City of Scottsdale, which
implemented an ASE program in the mid-2000s, ASE was effective in reducing speeding
and improving safety.85
Exhibit 7-1 – High-Level Overview of ASE Process
Like any type of enforcement methodology, ASE has its specific benefits and limitations.
Because automated speed enforcement does not require a law enforcement officer to be
present, it has the ability to continuously enforce the speed limit while freeing up officers
for other duties. ASE can also operate in areas, such as busy intersections, where in-
person traffic stops would be impractical or distracting to other drivers. ASE can be used
on higher speed roadways where traffic calming devices may not be appropriate. On the
other hand, ASE does not immediately stop speeding drivers. Furthermore, due to the
lack of direct contact between the officer and driver, there is no opportunity for
education, to observe suspicious activities and identify additional offenses (such as
impaired driving) nor does it afford the exercise of judgment in issuing a citation (such as
a written or verbal warning) that an officer would have. Exhibit 7-2 depicts the benefits
and limitations of ASE, as drawn from the NTSB’s study Reducing Speeding-Related
Crashes Involving Passenger Vehicles and NHTSA’s Speed Enforcement Camera
Systems Operational Guidelines.
83 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 37.
84 Ibid., 37.
85 Simon Washington, Evaluation of the City of Scottsdale Loop 101 Photo Enforcement Demonstration
Program (2017), 135.
Radar detects a
speeding vehicle
and triggers
camera
Camera captures
identifying information
(license plate and, if
needed, driver)
Back-office processor
processes violation and
matches information to
registration records
Citation is
mailed to
vehicle owner or
driver
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Exhibit 7-2 – Benefits and Limitations of ASE
Benefits of ASE Limitations of ASE
• Frees up law enforcement resources to
be used elsewhere and can serve as
“force multiplier”
• Driver does not stop and may continue to
speed
• Can operate where: 1) in-person traffic
stops would be dangerous; and 2) on
higher speed roadways where traffic
calming devices may not be appropriate
• Limited scope of enforcement and lack of
direct contact with motorists
• May reduce congestion from other
drivers distracted by traffic stops
• Time lag between violation and penalty
• Ability to continuously enforce speed
limit
• Challenged on several constitutional
grounds, including:
o Rights of due process
o Rights of equal protection
o Rights of privacy
• Proven to be an effective
countermeasure to reduce speed-
related crashes and injuries
• Criticized by the public as a tool to generate
revenue rather than increase safety
The NHTSA Speed Enforcement Camera Systems Operational Guidelines address the
considerations that should be taken into account when implementing and operating an
ASE program. The guidelines emphasize that an ASE program is supplement to, not a
replacement for, traditional law enforcement operations. The guidelines describe general
considerations and planning; program start-up; program operations; violation notice
processing and delivery; violation notice receipt and adjudication; and program
evaluation.
In addition to these general topics, NHTSA also provides more specific policy
considerations for any potential ASE program, many of which were echoed by Task
Force members. These considerations include:
• Locations • Public Notice
• Citation Type and Amount • Speed
• Warning Phase • Privacy and Use of Data
• Adjudication • Equity
• Use of Revenue • Camera Calibration
• Operation • Oversight
The Task Force spent some time discussing automated speed enforcement and its potential
safety benefit and the following recommendation for policy consideration reflects that. However,
it is important to acknowledge the sensitive and complex issues surrounding automated speed
enforcement.
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Although it is used extensively internationally, ASE has not been widely adopted in the U.S. at a
Statewide level. It is currently used in 142 U.S. cities and is not currently authorized in
California. In the late 1990s, the City of San Jose operated an ASE program but it was halted
following a judicial ban. As an effective speeding countermeasure, ASE is underutilized due to
various obstacles, including the lack of enabling legislation.86 According to NHTSA, which gives
ASE the maximum 5-star effectiveness rating, “many States have prohibitions in their laws to
prevent the use of automated enforcement technology; others have enabling legislation
and/or parameters on the use of the technology; and others still have no legislation that
addresses the technology’s use.”87
The importance of Statewide support for any ASE program is reflected in the NTSB’s 2017
recommendations on ASE in its Safety Study. It concludes that in order to be effective, ASE
programs need to be explicitly authorized by State legislation without operational and location
restrictions, and to this end, the NTSB recommended that all states remove obstacles to ASE
programs in order to increase its use.88
7.3. High Visibility Enforcement
A High Visibility Enforcement (HVE) strategy combines enhanced patrols, enhanced visibility
efforts, and publicity campaigns to educate the public and promote voluntary compliance with
the traffic laws. For example, an HVE campaign includes increasing patrols and blitzes,
installing visibility elements such as message boards and road signs, and implementing a
comprehensive communications and media plan. These efforts are coordinated and designed to
make enforcement efforts obvious to the public with the goal of changing driver behavior.
According to the NHTSA, which offers an online High Visibility Enforcement Toolkit, when the
perceived risk of getting caught by law enforcement goes up, the likelihood that people will
engage in unsafe driving behaviors goes down.89 Similarly, FHWA notes that traffic enforcement
is most effective when it is highly visible and publicized.90
Authorities must consider many factors when implementing an HVE campaign, including types of
enforcement (e.g., waves, saturation patrols, multi-jurisdictional); types of publicity (e.g., paid media,
earned media, social media), and types of visibility elements (e.g., electronic message boards,
billboards, specially marked squads). HVE programs can take 4 to 6 months to plan and incur
significant costs for both publicity and increased officer patrols. They require extensive time from the
State highway safety office and media staff and often from consultants to develop, produce, and
distribute publicity and time from law enforcement officers to conduct the enforcement.91
Communications and public outreach are an integral component of HVE programs. To assist
state and local agencies to plan and implement HVE programs, NHTSA annually prepares
resources for individual HVE program areas, including impaired driving, occupant protection
(e.g., Click it or Ticket), and distracted driving. Since states must conduct traffic safety
campaigns in order to receive some federal highway safety grant funds, national participation
rates are high.92
There is no national traffic safety campaign focused on the dangers of excessive speed
although campaign material is available from NHTSA. Likewise, California lacks a statewide
86 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 41.
87 NHTSA, Countermeasures that Work, 3-20.
88 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 54-57.
89 NHTSA, High Visibility Enforcement Toolkit (2019), “Visibility Elements.”
90 NHTSA, Countermeasures that Work, 8-36.
91 Ibid., 2-17.
92 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 49.
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speeding-related traffic safety campaign and HVE program. While the NTSB concludes that
“traffic safety campaigns that include highly publicized, increased enforcement can be an
effective speeding countermeasure, [however] their inconsistent and infrequent use by states
hinders their effectiveness.”93
The California OTS, in partnership with NHTSA, administers traffic safety grants to local and
state law enforcement agencies for programs to help them enforce traffic laws. HVE is promoted
as a best practice for enforcement operations, including impaired driving, distracted driving,
pedestrian and/or bicyclist safety, motorcycle safety, and other traffic enforcement operations
that target primary collision factors (including speed) within the jurisdiction.
From October 2016 to September 2017, the City of San Francisco conducted a HVE campaign
focused on speeding. The collaborative “Safe Speeds SF” campaign was led by the San
Francisco Municipal Transportation Agency (SFMTA) and the San Francisco Police Department
(SFPD), with the program evaluation led by the San Francisco Department of Public Health
(SFDPH). Law enforcement targeted 11 corridors on the city’s High Injury Network and these
enforcement efforts were accompanied by media campaigns and community outreach. During
the campaign over 1,800 speeding citations were issued to drivers on the HVE corridors.
Following its conclusion, researchers evaluated the campaign. Results indicated that HVE was
effective in lowering vehicle speeds during the enforcement period, and was modestly effective
in lowering vehicle speeds before and immediately after enforcement. However, these impacts
were not sustained in the long term and reductions in driver speeds began to diminish one week
after the HVE ended. SFDPH concluded that enforcement must be regular and sustained in
order to achieve lower vehicle speeds.94
93 Ibid., 50.
94 Vision Zero SF, Safe Speeds SF High Visibility Enforcement Campaign Findings (November 2019),
1-8.
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8.0 Additional Steps to Improve Safety
This section describes additional steps that can be taken to eliminate vehicular,
pedestrian, and bicycle fatalities on the road, including improving education
countermeasures, improving safety data, and linking crash and medical data to create a
more comprehensive understanding of traffic crashes.
8.1. Improving Education
Traffic safety campaigns use communications and outreach to increase public education
and awareness of a traffic safety topic. Nationally, NHTSA is responsible for coordinating
and sponsoring national traffic safety campaigns, address occupant protection (Click it or
Ticket), distracted driving (U Drive. U Text. U Pay.), and alcohol impairment, among
other issues. In California, the OTS coordinates with NHTSA to solve key highway safety
problems in the state by allocating federal funds to state and local agencies to
implement traffic safety programs and grants.
However, public awareness of the dangers of speeding is lacking at both the federal
and state level. There is no national campaign devoted to speeding, and, given this
absence, “there is incomplete participation among states, and little consistency among
the individual state campaigns.”95 The NTSB found that the dangers of speeding are not
well-publicized and that citizens generally underappreciate the risks of speeding. While
other traffic safety issues are highly visible and have national leadership, speeding lacks
this support, especially when contrasted with more visible campaigns:
A 2011 study found that 32 states funded public awareness efforts for speeding;
25 of these states reported using a total of 30 different campaign slogans, and 8
states used the NHTSA slogans. In contrast, all 50 states participate in the
national occupant protection campaign, and they all use the campaign’s “Click It
or Ticket” slogan. Participation in the NHTSA-coordinated, national traffic safety
campaigns is high because states are required to participate in order to receive
some federal highway safety grant funds.96
Currently, California lacks a state funding mechanism for a statewide coordinated traffic
safety campaign focused on speeding. As the state leader in behavioral traffic safety,
OTS is in the unique position to create campaigns and marketing that can change
roadway user’s behavior and decrease fatalities throughout the State. OTS directs $4.5
million in federal funding each year to marketing activities and public awareness
campaign planning and execution, video and audio public service announcement (PSA)
production, social media, media event planning, print, and graphic materials. The current
funding level limits the amount of marketing, public relations and outreach related to
traffic safety (with a focus on speeding) to the ethnically diverse population of 39 million
Californians. The California Department of Public Health can also be consulted in the
design, evaluation, and dissemination of evidenced-based campaigns. CDPH created
the campaign, “It’s Up to All of Us,” which could be reintroduced to help increase
awareness of the dangers of vehicle speeding to pedestrians and bicyclists. There are
numerous ongoing traffic safety campaigns being implemented at the regional and local
levels. An example of a regional campaign is the Southern California Association of
95 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 49.
96 Ibid., 49.
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Governments (SCAG’s) Go Human campaign, which is a community outreach and
advertising campaign, with the goals of reducing traffic collisions and encouraging
people to walk and bike more. Go Human deploys regional media campaigns (radio,
social media, gas pump ads, billboards, and print media), local co-branding partnerships
via advertisements and events, and demonstration projects.
Education countermeasures can change public knowledge, attitudes, and behavior
related to speeding, especially when combined with enforcement campaigns. Public
campaigns and education can promote a culture of safety-consciousness and research
has shown that the communications component of a traffic safety campaign increases
safety benefits; for example, a review of traffic safety campaigns in 12 countries
found that public information and education reduced crashes by 9% on average.97
Improving the education and public outreach regarding the dangers of excessive speed
represents an important step that can be taken to help eliminate crashes, serious
injuries, and fatalities on California’s roadways.
8.2. Improving Safety Data
At both a federal and statewide level, the limitations of speeding-related crash data
poses another challenge to the practitioners who evaluate and implement
countermeasures to increase safety. Common limitations include poor data quality, lack
of timeliness, underreporting, and inconsistencies. Yet according to NHTSA, “states
need timely accurate, complete, accessible, and uniform traffic records to identify and
prioritize traffic safety issues and to choose appropriate safety countermeasures and
evaluate their effectiveness.”98
Based on its analysis of the national Fatality Analysis Reporting System (FARS), the
NTSB found that involvement of speeding passenger vehicles in fatal crashes is
underestimated and that “the lack of consistent law enforcement reporting of speeding-
related crashes hinders the effective implementation of data-driven speed enforcement
programs.”99 Similarly, within the context of pedestrian and bicyclist safety, NHTSA
found that pedestrian and bicyclist crashes tended to be underreported.100
For the purposes of crash reporting, “speeding” is used to identify vehicles that are
traveling at speeds which are: 1) unsafe for conditions or 2) exceed the speed limit.
Speeds that are unsafe for conditions are based on basic speed law which is defined as
driving at a speed greater than is reasonable or prudent considering weather, visibility,
traffic, and roadway conditions. Because the definition of speeding includes these two
different conditions, it is unknown to what degree exceeding a posted or statutory speed
limit contributes to the total number of speeding-related crashes.
Current crash data is required to make evidence-based traffic safety funding decisions,
inform enforcement activities, and help direct critical infrastructure investments. The CHP
has made substantial progress toward the goal of statewide electronic crash report
submission and automated crash data collection. Internally, beginning in 2016, the CHP
deployed a fully paperless electronic crash reporting system. Once a completed CHP
crash report is approved at the local level, it is electronically submitted, and pertinent
crash data is captured in SWITRS. From 2017 to present, 100 percent of CHP generated
97 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 48.
98 NHTSA, Traffic Records Program Assessment Advisory (2018), 2.
99 NTSB, Reducing Speeding-Related Crashes Involving Passenger Vehicles, 32-33.
100 NHTSA, Countermeasures that Work, 8-5.
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crash reports are processed electronically; this represents approximately 46 percent of
crash reports statewide. The benefits of the system include near real-time submission of
crash reports, as well as enhanced quality control due to business rules and filters built
into the programming that prevent entry of data incompatible with the field filled.
In 2019 the CHP expanded this program by developing a Web portal to permit allied
agencies outside the CHP to also submit crash reports to SWITRS electronically. The
first participating allied agency, Bakersfield Police Department, began submitting
electronic crash reports in March 2019. To date, there are four allied agencies fully
utilizing the Web portal for electronic crash report submission, and five additional
agencies submitting reports in a test environment. Those agencies in the test
environment continue to batch and forward printed crash reports. The CHP continues to
engage with crash reporting software vendors to accelerate the on-boarding of client
agencies. Currently one vendor has achieved full integration; two additional vendors are
in the testing process.
Although the CHP has received relatively few allied agency crash reports electronically
through the Web portal (2,174 as of November 2019), the impact on timeliness has been
dramatic. Using 2019-to-date data, the raw average time from the day of crash to data
entry in SWITRS for a non-electronically submitted crash report is 81 days. Crash
reports submitted by agencies using an electronic format and the Web portal are entered
into SWITRS in an average of 6 days.
While progress has been made, there are still opportunities to expedite allied agencies’
submissions of traffic crash data reports electronically. Specifically, NHTSA offers
federal grants to improve the timeliness, accuracy, completeness, uniformity,
accessibility, and integration of the crash data. Within California, OTS administers these
405(c) grants and is prepared to award these grants to local law enforcement agencies
to assist in efforts to electronically transmit crash records into the SWITRS system.
Expediting allied crash reports into SWITRS will provide significant improvement in traffic
crash data availability.
8.3. Linking Crash and Medical Data
Transportation professionals and policymakers have long relied on crash data collected
at the scene by law enforcement officials to inform traffic safety decisions. Yet recent
efforts have highlighted the limitations of crash data and the corresponding opportunity
to improve it by linking it with medical data. According to the Collaborative Sciences
Center for Road Safety, a federally-funded academic research project, “traditionally,
safety and injury analysis have occurred in isolated fields, with road safety researchers
relying predominately on police-recorded crash reports, and public health researchers
relying on health records (e.g., hospital, emergency department, and ambulatory care
data).”101 This division has led to an incomplete and inconsistent picture of traffic
crashes, with different records reflecting different findings. For example, research
comparing police data reported in SWITRS (California’s Statewide Integrated Traffic
Records System) and San Francisco hospital data found that police records did not
include approximately 20% of pedestrian injuries and 25% of cyclist injuries.102
101 Collaborative Sciences Center for Road Safety, Completing the Picture of Traffic Injuries:
Understanding Data Needs and Opportunities for Road Safety (2018), 2.
102 San Francisco Department of Public Health (SFDPH), San Francisco’s Transportation-related Injury
Surveillance System (2017), 1.
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Efforts to provide a more complete picture of transportation-related injuries by linking
existing traffic and health data were initiated at the national level in the early 1990s.
From 1992 to 2013 NHTSA worked with individual states to develop data linkage
programs under the Crash Outcome Data Evaluation Systems (CODES). In 2013,
CODES was discontinued and some states retired their programs while others have
continued their data linkage projects independently. In California, the Department of
Public Health maintains the statewide data linkage effort through the Crash Medical
Outcomes Data (CMOD) Project, which electronically links police crash reports with
health and death data. This dataset enables policymakers and professionals to
understand the geographic distribution, causes, costs, and consequences of traffic
injuries and fatalities, and ultimately to develop targeted injury prevention strategies to
eliminate them.
At the local level, the San Francisco Department of Public Health spearheaded the effort
to develop the Transportation-related Injury Surveillance System (TISS). In 2017, San
Francisco was the first city in the country to use the resulting linked data to update its
High Injury Network (HIN) and analyze spatial patterns of severe and fatal injuries. With
this more robust data, San Francisco was able to identify locations of unreported traffic
injuries, better capture injury severity, and focus its HIN on the most severe outcomes.103
Cities that want to create their own linked datasets must confront a key challenge, namely
the need to accurately link records while also adhering to privacy laws for personally
identifiable information (PII) and protected health information (PHI). While there are many
linkage methodologies, the quality and success of the linkage is highly dependent on
multiple unique identifiers that are subject to privacy laws such as name, date of birth,
and other personally identifying information.104 For example, law enforcement does not
usually collect social security numbers, and if they do so, this information is subject to the
Health Insurance Portability and Accountability Act (HIPAA).105
Such factors must be kept in mind as part of the renewed interest in developing linked
datasets, which can provide a more complete picture of traffic injuries and fatalities and,
ultimately, help policymakers develop strategies to prevent them.
103 SFDPH, San Francisco’s Vision Zero High Injury Network: 2017 Update (2017), 2.
104 Collaborative Sciences Center for Road Safety, Completing the Picture of Traffic Injuries, 3-4.
105 Ibid., 3.
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9.0 Findings and Recommendations for Policy
Consideration
The findings and recommendations for policy consideration (recommendations) are organized
as follows (not in priority order):
• Establishing Speed Limits (S)
• Engineering (EN)
• Enforcement (EF)
• Education (ED)
Findings are abbreviated as “F.” Recommendations are abbreviated as “C.” In some cases, a
finding may have multiple recommendations
The recommendations have been developed based on input from the Task Force, Advisory
Group, the literature synthesis prepared by the University of California Institute of Transportation
Studies (UC ITS), and other research findings. It is important to note that all Task Force
members may not agree with all the findings and recommendations. These recommendations
are being offered for further policy discussion and review by interested stakeholders and do not
reflect an official position or endorsement of the Administration. The following Guiding Principles
were established for the recommendations:
1. Data-driven / evidence based: studied and shown to be effective in improving safety.
2. Implementable statewide: supported and realistic to implement statewide, for both State
and local agencies.
3. Supports partnerships and innovation: inclusive of the multiple disciplines with traffic
safety and would benefit from a partnered approach across state, regional, local, and
external stakeholders.
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9.1. Establishing Speed Limits (S) – Findings and Recommendations
for Policy Consideration
F-S1: Existing law does not provide enough flexibility in urban areas to set speed
limits that are appropriate for these complex environments.
Current procedures for setting speeds limits in California rely mainly on the 85th
percentile methodology, an approach developed decades ago for vehicles primarily on
rural roads. Although California’s population, roads, and streets have changed
significantly, reflecting different modes of transportation including bicycling and walking,
the method for setting speed limits has not. While the way that speed limits are
calculated has remained essentially static, vehicles and street uses have evolved over
time. CalSTA’s vision is to transform the lives of all Californians through a safe,
accessible, low-carbon, 21st-century multimodal transportation system. Yet the 85th
percentile methodology relies on driver behavior. Greater flexibility in establishing speed
limits would allow agencies an expanded toolbox to better combat rising traffic fatalities
and injuries.
F-S2: Developing a different approach to setting speed limits would enable the
State to prioritize safety outcomes to meet the needs of all road users.
The current approach to setting speed limits relies on driver behavior. With fatalities and
serious injuries on the rise, many authorities are reevaluating this current approach.
Consistent with international trends, other U.S. states, including Oregon, Washington,
Minnesota, and New York, are enabling their cities to lower their speed limits and are
exploring alternative methods to establish speed limits based on safety goals and local
context instead of the 85th percentile speed. California has the opportunity to reevaluate
how it sets speed limits to develop a new approach that prioritizes safety for all road users.
Number Recommendation for Policy Consideration
C-S1 Develop and implement a new roadway-based context sensitive approach to
establish speed limits that prioritizes the safety of all road users. This approach
should be based on how a street is used and by whom, how protected non-
motorized users are from vehicles, how likely it is that there will be a conflict
between vehicles and other street users, and how likely it is that a collision will
result in a fatal or serious injury.
Possible implementation steps may include convening an expert advisory
group in 2020 to evaluate national and international data-driven approaches to
establishing speed limits; examine evidence-based research; and solicit public
input and comment.
Note: This is a long-term recommendation. In contrast, the recommendations
regarding changes to the speed-limit-setting process are short-term.
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F-S3: Recent research has demonstrated that reducing posted speed limits
reduces vehicle operating speeds and improves safety across most road
environments.
Current evidence supports the use of reducing speed limits to increase safety in general.
In a research synthesis commissioned specifically for this report, the University of
California, Institute of Transportation Studies found that reducing posted speed limits
also reduces drivers’ operating speeds and improves safety across most road
environments. While reducing posted speed limits only reduce drivers’ operating speeds
by a few miles per hour, these small changes in operating speed result in meaningful
safety improvements. This is especially the case for environments with vulnerable road
users as they greatly benefit from even small changes in operating speeds. Although
historical research between safety and speed asserted that posting the speed limit at the
85th percentile speed resulted in the lowest crash rate, recent studies indicate that there
is not strong evidence to support this claim.
F-S4: Current procedures for establishing speed limits do not offer agencies
enough flexibility to set appropriate speed limits.
The process for setting speed limits through engineering and traffic surveys does not
require consideration of factors such as road use and pedestrian and bicyclist safety.
Although engineers may consider additional factors to the 85th percentile speed and
crash history when establishing speed limits, many stakeholders believe that
consideration of these other factors should be required and prioritized. In addition, speed
data collection procedures are not always thorough enough to reflect the complexity of
the street. In the two-step process to establish speed limits, engineers determine the 85th
percentile speed and may then apply rounding allowances to arrive at a lower, adjusted
speed limit. However, the procedures limit these allowances and adjustments. Many
stakeholders, including local agencies and CalSTA departments, believe that the current
procedures are overly restrictive and prevent the establishment of appropriate speed
limits. Further, fatal and serious crashes are often clustered on a relatively small number
of streets/areas (i.e., High Injury Networks and high collision concentration locations)
and disproportionately impact vulnerable road users yet existing rounding allowances do
not allow further reduction in speed in these areas.
Number Recommendations for Policy Consideration
C-S2
Once the National Cooperative Highway Research Program (NCHRP) 17-76
“Guidance for the Setting of Speed Limits” research project is complete
(anticipated summer 2020), and the final report published, explore
implementation of the research results. A realistic assessment includes
examining the applicability of the research results for California as well as any
impediments to implementation.
C-S3 Revise traffic survey procedures to specifically require consideration be given to
bicyclist and pedestrian safety and develop guidance to describe how to
consider bicyclist and pedestrian safety in a traffic survey.
C-S4 Allow state and local agencies to post speed limits below 25 mph when
supported by a traffic survey.
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Number Recommendations for Policy Consideration
C-S5 Increase the reduction allowance for posted speed limits to allow greater
deviations from the 85th percentile speed. Currently, the posted speed may only
be reduced by 5 mph from the nearest 5 mph increment of the 85th percentile
speed. Classes of locations where the posted speed may be reduced further
should include:
• High Injury Networks (HIN). Steps to implement include developing a
statewide definition of a HIN. Possible criteria may include:
o A minimum of three years of the most current crash data
o Weighting of fatal and serious injury crashes
o Weighting of crashes that occurred in disadvantaged
communities
The resultant HIN should: identify specific locations with high crash
concentrations; identify corridor-level segments with a pattern of crash
reoccurrence; and be able to be stratified by mode.
• Areas adjacent to land uses and types of roadways that have high
concentrations of vulnerable road users. Steps to implement include
defining vulnerable populations (e.g., pedestrians, bicyclists, scooter
users, transit users, seniors, children) and developing criteria to identify
eligible streets (e.g., streets close to transit centers, homeless shelters,
urban parks/playgrounds, and healthcare facilities as well as types of
streets like bicycle boulevards and neighborhood greenways).
F-S5: There is consistent evidence that increased vehicle speed results in an
increased probability of a fatality given a crash. Vulnerable road users are
disproportionately impacted by the relationship between speed and crash
survivability. State and local agencies would benefit from additional classes of
locations eligible for prima facie speed limits which do not require an engineering
and traffic survey.
Prima facie speed limits are those that are applicable on roadways when no posted
speed limit is provided. They do not require an engineering and traffic survey to be
enforceable. Current law defines two prima facie speed limits covering six classes of
locations. The first speed limit is 25 mph and is applicable to business and residential
areas, school zones and areas around senior facilities. The second speed limit is
15 mph and is applicable to railway crossings, uncontrolled intersections and alleyways.
Some allowances are currently provided to reduce these speed limits further, for
example, to 15 mph and 20 mph in school and senior zones. State and local agencies
on the Task Force stated that additional classes of locations should be eligible for prima
facie speed limits especially in areas that have high concentrations of vulnerable road
users.
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Number Recommendations for Policy Consideration
C-S6 Add “business activity district” as an additional class of location eligible for a
prima facie speed limit. Steps to do this include developing a statewide
"business activity district” definition which could include urban villages,
neighborhood downtowns, and other business-oriented locations. Ensure
“business activity district” prima facie speed limits are applicable to the State
Highway System.
Note: Consideration should be given to the existing statutory definition of a
Business District which is based on a land use/geography definition and does
not accurately reflect the characteristics and use of streets within a dense urban
business/downtown area (e.g., high volume of road users and frequent street
crossings). Currently, the State Highway System is not eligible for prima facie
speed limits in Business Districts.
C-S7 Revise requirements related to posting prima facie speed limits in school zones
(i.e., a reduced “When Children are Present” speed limit):
a. Allow an authority to determine and declare a prima facie speed limit as
low as 15 mph without requiring justification by a traffic survey.
Currently, if a local jurisdiction wants to lower the speed limit in a school
zone below 25 mph they must conduct a traffic survey unless the local
jurisdiction passes an ordinance and the road geometry meets specific
conditions stipulated in the CVC.
b. Expand the roadway conditions that allow for school zone prima facie
speed limits. Currently, the prima facie limits for school zones only
applies to roadways that have certain posted speed limits and a limited
number of traffic lanes.
c. Clarify the definition of “WHEN CHILDREN ARE PRESENT.” Currently,
school zone prima facie limits are only applicable when children are
present, however the meaning of “when children are present” is
subjective.
F-S6: Current procedures for establishing speed limits have produced the unintended
consequence of speed creep, or rising vehicle operating speeds over time.
Studies have shown that using the 85th percentile speed to establish speed limits has
increased drivers’ operating speeds as an unintended consequence. Raising speed
limits to match the 85th percentile speed of vehicles leads to higher operating speeds,
which can then contribute to a higher 85th percentile speed. Research has shown that
over time, vehicle operating speeds continue to increase even if the road and vehicle
conditions remain the same.
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Number Recommendation for Policy Consideration
C-S9 Allow for a traffic survey to retain the existing speed limit (or revert to one
determined in a prior traffic survey) unless a registered engineer determines
that significant design changes have been made to the roadway since
completion of the last traffic survey with the specific intent of increasing the safe
operating speed.
Currently, if a speed survey shows that vehicle operating speeds have
increased, agencies must raise the posted speed limit even if the roadway
design has not changed, contributing to speed creep over time.
F-S7: State and local agencies need statutory clarification on the rules,
procedures, and exceptions to posted speed limits.
The rules and procedures governing posted speed limits are found in an inconsistent set
of codes and manuals, including the California Vehicle Code and the California Manual
for Setting Speed Limits. Many stakeholders, including local agencies and CalSTA
departments, find some of the statutory language in these sources unclear and
ambiguous. For example, speed allowances in senior zones need to be clarified.
Technical clarification may help agencies better understand how and under what
conditions speed limits below the 85th percentile speed can be established.
Number Recommendation for Policy Consideration
C-S10 Consolidate and clarify statutory sections related to speed setting methodology.
F-S8: State and local agencies would benefit from a single source of guidance on
how to establish speed limits.
California is divided into 58 counties and 482 cities. Many large local agencies are familiar
with policies, procedures, and statutory mandates on posted speed limits and prima facie
zones. However, smaller jurisdictions are not as well-versed in these topics and some are
unaware of the myriad of existing rules that allow them to deviate from the 85th percentile
speed. The opportunity exists to provide consistent step-by-step guidance for state and
local agency staff on how to establish speed limits below the 85th percentile speed.
Number Recommendations for Policy Consideration
C-S11 Revise the California Manual for Setting Speed Limits to comprehensively
cover speed setting methodology and law in easy to understand terminology.
This update should be guided by a committee of state and local subject matter
experts. New material should include guidance on developing a High Injury
Network (HIN) and any new methods developed in the future.
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Number Recommendations for Policy Consideration
C-S12 Develop state-sponsored training on the California Manual for Setting Speed
Limits. The training should include general speed concepts, regulatory and
advisory speeds, engineering and traffic survey procedures, renewal
requirements, common misconceptions, FAQs as well as any new methods
developed in the future. The audience for this training would include city
officials, state and local traffic engineers, state and local law enforcement, legal
staff, judicial council, and traffic safety practitioners.
C-S13 Establish technical assistance resources, including a webpage, to provide
practitioners with an overview of speed setting methodology, best practices,
and case studies, as well as any new methods developed in the future. Provide
State support to local agencies with less capacity to develop HINs by providing
a resource that summarizes existing data and mapping tools available to
develop a network.
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9.2. Engineering (EN) – Findings and Recommendations for Policy
Consideration
F-EN1: Engineering countermeasures designed to reduce vehicle operating
speeds can be costly and time-consuming to implement.
Roadway engineering solutions range from low-cost options such as pavement markings
and signs to complex, multi-million-dollar construction projects such as roundabouts.
Especially for large-scale engineering designs, there are many barriers to
implementation, including lengthy and costly approval, permitting, funding, and
construction processes.
Number Recommendations for Policy Consideration
C-EN1 Review and consider revising the allocation of Highway Safety Improvement
Program (HSIP) funds between local roads and the State Highway System
(SHS) from a data-driven perspective. Analyze the current HSIP allocations
and determine if revisions to the allocations could improve statewide safety
outcomes. As part of the evaluation, review other funding sources (e.g., sales
tax measure funds) and amounts for both State and local safety projects.
Currently, the total HSIP funding allocation received from the federal
government is divided in approximately equal amounts between local roads
and the SHS.
C-EN2 Regularly review the Caltrans encroachment permitting process to identify
inefficiencies and determine new methods to expedite safety-related projects.
In 2019, Caltrans implemented a Lean 6 Sigma project to decrease the time
needed to approve or deny an encroachment permit application. Regular
evaluation would provide an opportunity to make modifications in order to
continually improve this process.
F-EN2: Agencies who want to lower the operating speed of vehicles to improve
safety using engineering interventions would benefit from Statewide policies,
guidance, and standards.
While large cities such as San Francisco and Los Angeles have developed their own
engineering and design guides, smaller cities do not have the resources to produce their
own standards and rely on a variety of other sources. This includes federal guidelines,
guidance produced by professional associations, and the Caltrans’ Highway Design
Manual (developed for State highway design functions). Currently, no definitive
document exists that provides agencies with comprehensive engineering and design
standards to design low speed roadways that prioritize people walking, bicycling, and
taking transit. For instance, the Caltrans Highway Design Manual does not include
standards for many types of horizontal and vertical traffic calming devices.
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Number Recommendations for Policy Consideration
C-EN3 Develop policies related to the following topics and incorporate them into the
Highway Design Manual:
• Traffic calming
• Lane narrowing
• Reallocation of the roadway cross-section
• “Target speed”
Note: While Design Speed is a selected speed used to determine the various
geometric features of the roadway, the “Target Speed” is the intended velocity
for drivers. The intent of “target speed” is to geometrically redesign roadways in
order to decrease operating speed. The topic of “Design Speed” versus “Target
Speed” typically centers on roadways with speed limits between 25 mph and
45 mph especially where the 85th percentile speed is higher than the posted
speed limit.
C-EN4 Require Caltrans to regularly convene a committee of external roadway design
experts to advise on revisions to the Highway Design Manual. Meetings of this
committee will serve as a forum to gather, review and evaluate proposals
concerned with rules and regulations prescribing design standards contained in
the Highway Design Manual (HDM). This committee will develop an
experimentation process for design standards not currently in the HDM and
procedures for updating the HDM based successful experiments. Through the
California Traffic Control Devices Committee (CTCDC), Caltrans is able to fulfill
statutory requirements to consult with local agencies (and the public) before
revising the California Manual on Uniform Traffic Control Devices (CA
MUTCD). The intent is to develop a committee, similar to the CTCDC in
concept, to provide guidance on the Caltrans Highway Design Manual.
Consideration should be given to including public health professionals in the
newly formed Caltrans’ design committee.
C-EN5 Formalize existing traffic control device uses in the CA MUTCD. The purpose
of traffic control devices is to promote safety and efficiency by providing for the
orderly movement of all road users. Develop and conduct a biennial
survey to understand how agencies are implementing traffic control devices
then analyze whether updates to the CA MUTCD should be made through the
CTCDC or whether statewide experiments should be created.
C-EN6 Develop a statewide traffic safety monitoring program that identifies and
addresses locations with speeding-related crashes, with the long term goal of
substantially reducing speeding-related fatalities and serious injuries. Newly
developed traffic calming devices (see C-EN3) will be the toolbox for this
speeding-related monitoring program. An evaluation of the completed
monitoring program investigations will help to inform a possible
recommendation on modification to the definition of “speeding-related” in crash
reporting.
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Number Recommendations for Policy Consideration
C-EN7 Make the pilot State-led traffic safety monitoring programs that identify and
address locations with pedestrian- and bicyclist-related crashes permanent.
Expand this pilot to include both reactive (i.e., crash-based) location
identification, proactive (i.e, systemic) location identification and all public roads
(i.e., on and off SHS) . Currently, there are four ongoing traffic safety
monitoring programs that identify and address locations statewide that have
experienced vehicle-related crash types but none of these programs provide
regular mechanism to evaluate and improve locations for pedestrian- and
bicyclist-safety.
F-EN3: Local agencies voiced concern about the impact of Level of Service
requirements on their efforts to lower vehicle operating speeds through
engineering interventions.
In city planning documents, through state permitting processes, and through the
environmental review process, acceptable vehicle Levels of Service (LOS) for specific
roadways is often identified and used in order to avoid excessive traffic congestion and
delay. LOS is a metric used by engineers to rate the quality of traffic operating conditions
on a scale from best (A) to worst (F) and to define what level is acceptable. While further
investigation is needed, preliminary findings suggest that the need to maintain or
improve Level of Service is a barrier for local jurisdictions who want to design their roads
for slower speeds to accommodate other road users such as bicyclists and pedestrians.
Number Recommendations for Policy Consideration
C-EN8 Further investigate the impact of Level of Service requirements on the
implementation of engineering interventions designed to reduce operating
speed.
C-EN9 With the implementation of Senate Bill 743 (Chaptered 2013), LOS will be
replaced by Vehicle Miles Traveled (VMT), including induced demand analysis,
as a new metric for transportation analysis under the California Environmental
Quality Act (CEQA). Caltrans is developing guidance on VMT analysis and
associated safety analysis for both SHS projects and local land use projects
through CEQA. In order to increase positive safety outcomes:
• Through the Local Development-Intergovernmental Review (LD-IGR)
process, minimize using or requesting LOS analysis as a measurement
of safety for local land use projects with potential impacts to the SHS,
particularly in low VMT areas (as defined by the SB 743 Technical
Advisory).
• Develop LD-IGR guidance, to be used by Caltrans and local agencies as
part of SB 743 implementation, that is based on the latest safety
research.
• Sufficiently train Caltrans and local agency staff to implement SB 743
including the safety analysis component.
• Update state-aid local assistance project selection criteria to reflect
SB 743 requirements.
• Coordinate and collaborate with the federal government so that federal-
aid programs allow VMT analysis and mitigation instead of LOS analysis.
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9.3 Enforcement (EF) – Findings and Recommendations for Policy
Consideration
F-EF1: International and U.S. studies have shown that automated speed
enforcement is an effective countermeasure to speeding that can have
meaningful safety impacts.
Automated speed enforcement systems work by capturing data about a speed violation,
including images and license plate information, which is then reviewed and processed at
a later time to determine if a violation occurred. Currently, automated speed enforcement
is used extensively internationally and in 142 communities in the U.S. Numerous studies
and several federal entities, including the National Transportation Safety Board, have
concluded that automated speed enforcement is an effective countermeasure to reduce
speeding-related crashes, fatalities, and injuries.
F-EF2: Automated speed enforcement should supplement, not replace,
traditional enforcement operations.
According to the Federal Highway Administration’s Speed Enforcement Camera
Systems Operational Guidelines, automated speed enforcement is a supplement to, not
a replacement for, traditional traffic law enforcement operations. Automated speed
enforcement systems can effectively augment and support traditional enforcement
operations in multiple ways. Automated speed enforcement systems serve as a “force
multiplier” that allows limited law enforcement resources to focus on other public safety
priorities. ASE can be operated in areas where in-person traffic stops would be
impractical as well as on higher speed roadways where traffic calming devices may not
be appropriate. While ASE does not provide an educational opportunity nor afford the
exercise of judgment in issuing a citation that an officer would have from an in-person
stop, it may also provide for more consistent and impartial enforcement. Examples of
cities that have deployed automated speed enforcement programs without reducing law
enforcement staffing levels include Seattle, Portland, and Washington, D.C.
Number Recommendation for Policy Consideration
C-EF1 Use of automated speed enforcement should supplement, not supplant,
existing law enforcement personnel.
F-EF3: Many complex public policy considerations must be taken into account to
develop and implement an automated speed enforcement program.
When developing an automated speed enforcement program, policy makers confront a
number of key decisions. The many complicated and sensitive issues that must be
addressed prior to implementation include citation amount, citation type, equity, camera
locations, privacy and data use, public noticing, and speed tolerance level. In evaluating
and making decisions regarding automated speed enforcement programs, policies and
proposed practices need to be fully and transparently vetted through meaningful public
awareness, education, and engagement.
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Number Recommendations for Policy Consideration
C-EF2 Automated speed enforcement (ASE) guidelines could take into consideration
the following relevant policy issues, which would need to be fully and
transparently vetted within the impacted communities to ensure equitable
outcomes:
• Citation Amount – The citation amount needs to deter speeders but
should not be so large that it criminalizes those who cannot afford to
pay the penalty.
• Citation Type – In addition to considering the merits of either a civil and
criminal citations, contemplate adding a warning phase” with the initial
program launch where only warnings (not citations) would be issued.
• Locations – The location(s) any automated speed enforcement system
may be determined based on a data-driven safety analysis.
• Privacy – ASE programs may incorporate best practices in surveillance
technology.
• Public Noticing – Determine the method(s) used to notify the community
of the automated speed enforcement program, including advance
hearings, signage, and ongoing electronic notification systems. Noticing
should include education that articulates the relationship between crash
severity and individual vehicle speed.
• Speed tolerance level – For consistency, explore establishing Statewide
minimum speed tolerance levels, based on either a percentage or
absolute amount of the posted speed limit. Some Task Force members
observed that if speed tolerances are too low communities grow
frustrated due to minor speedometer variances; if the tolerance is too
high then law enforcement is communicating that the posted speed is
too low for the conditions. The IHHS states that most automated speed
enforcement tickets are triggered going at least 10 to 11 MPH over the
posted speeds, although the tolerance is lower in certain locations such
as school and work zones.
• Incorporate Lessons Learned – ASE guidelines should take into
consideration existing State regulations for red light cameras as well as
on Community Control Over Police Surveillance (CCOPS) practices
whenever possible.
C-EF3 Develop strategies to eliminate any incentive that could turn an automated
speed enforcement program into a revenue generation technique. Ideas raised
by the Task Force included:
• Earmark all automated speed enforcement revenue to solely administer
the program and for traffic safety road investments.
• Do not allow the entities that establish the speed tolerances, the penalty
amount, enforcement locations, and other decisions that impact the
automated speed enforcement revenue to financially benefit from their
policy decisions.
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Number Recommendations for Policy Consideration
• Pay the automated speed enforcement vendor a fixed price for
competitively-procured equipment and services, rather than the amount
of revenue collected.
F-EF4: Traffic safety enforcement is not prioritized amongst all law enforcement
agencies Statewide.
Traffic safety enforcement is not prioritized amongst all law enforcement agencies
Statewide. Following the recession of 2008, law enforcement agencies severely cut back
their resources for traffic safety enforcement activities. Traffic fatalities have been on an
upward trend since 2010 and many local law enforcement agencies have not returned to
pre-recession staffing. Without funding from the OTS, some areas of the state would not
have dedicated traffic safety enforcement. Economists are now predicting another
economic downturn soon and many of these agencies are still not operating at full staff.
Number Recommendation for Policy Consideration
C-EF4 Convene a forum where law enforcement agencies Statewide can discuss
issues and barriers to consistent and continual traffic safety enforcement.
• The goal of the forum would be to share best practices and develop
recommendations to overcome the lack of prioritization of traffic safety
enforcement across the State.
• This event would keep local law enforcement engaged in traffic
enforcement operations and reinforce the need for traffic safety
enforcement.
• This event should include a focus on data-driven, evidence-based
strategies to provide for consistent and continual traffic safety
enforcement.
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9.4. Education (ED) – Findings and Recommendations for Policy
Consideration
F-ED1: Traffic safety education is an important countermeasure to speeding but
California lacks sufficient mechanisms for coordinated traffic safety campaigns.
Education countermeasures can change public knowledge, attitudes, and behavior
related to speeding, but California lacks a coordinated traffic safety campaign. As the
state leader in behavioral traffic safety, the OTS can create safety campaigns that can
change roadway user’s behavior and decrease fatalities throughout the State. The
California Department of Public Health can also be consulted in the design, evaluation,
and dissemination of evidenced-based campaigns. Furthermore, there are opportunities
for both the California Highway Patrol and the Department of Motor Vehicles to reinforce
traffic safety education as well as opportunities to coordinate with current ongoing traffic
safety campaigns being implemented at the regional and local levels. California has the
opportunity to provide comprehensive, multi-agency, coordinated outreach on the
dangers of speeding to the diverse population of 39 million Californians.
Number Recommendation for Policy Consideration
C-ED1 Develop a statewide coordinated traffic safety campaign to:
• Inform and educate the California population at large on how they can
travel safely and abide by the laws of the road.
• Prioritize public awareness, outreach, and education on traffic safety
and the dangers of excessive speed.
• Expand the reach of individual campaigns being impleented at regional
and local levels, and leverage investment through coordinated
messaging, visuals, and branding.
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10.0 Appendices
A. AB 2363 – Zero Traffic Fatalities Task Force
CHAPTER 8. Zero Traffic Fatalities Task Force
CVC Section 3095.
(a) On or before July 1, 2019, the Secretary of Transportation shall establish and
convene the Zero Traffic Fatalities Task Force.
(b) The task force shall include, but is not limited to, representatives from the
Department of the California Highway Patrol, the University of California and other
academic institutions, the Department of Transportation, the State Department of
Public Health, local governments, bicycle safety organizations, statewide motorist
service membership organizations, transportation advocacy organizations, and labor
organizations.
(c) The task force shall develop a structured, coordinated process for early engagement
of all parties to develop policies to reduce traffic fatalities to zero.
CVC Section 3096.
(a) The Secretary of Transportation shall prepare and submit a report of findings based
on the Zero Traffic Fatalities Task Force’s efforts to the appropriate policy and fiscal
committees of the Legislature on or before January 1, 2020.
(b) The report shall include, but is not limited to, a detailed analysis of the following
issues:
(1) The existing process for establishing speed limits, including a detailed discussion
on where speed limits are allowed to deviate from the 85th percentile.
(2) Existing policies on how to reduce speeds on local streets and roads.
(3) A recommendation as to whether an alternative to the use of the 85th percentile
as a method for determining speed limits should be considered, and if so, what
alternatives should be looked at.
(4) Engineering recommendations on how to increase vehicular, pedestrian, and
bicycle safety.
(5) Additional steps that can be taken to eliminate vehicular, pedestrian, and bicycle
fatalities on the road.
(6) Existing reports and analyses on calculating the 85th percentile at the local,
state, national, and international levels.
(7) Usage of the 85th percentile in urban and rural settings.
(8) How local bicycle and pedestrian plans affect the 85th percentile.
CVC Section 3097.
This chapter shall remain in effect only until January 1, 2023, and as of that date is
repealed.
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B. University of California, Institute of Transportation Studies,
Research Synthesis
See attached document.
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C. List of Abbreviations
ASE – Automated Speed Enforcement
Caltrans – California Department of Transportation
CA MUTCD – California Manual on Uniform Traffic Control Devices
CDPH – California Department of Public Health
CHP – California Highway Patrol
CMF – Crash Modification Factors
CMOD – California Crash Medical Outcomes Data Project
CODES – Crash Outcome Data Evaluation Systems
CVC – California Vehicle Code
E&TS – Engineering and traffic survey
FHWA – Federal Highway Administration
HIN – High Injury Network
HVE – High Visibility Enforcement
LOS – Level of Service
NACTO – National Association of City Transportation Professionals
NCHRP – National Cooperative Highway Research Program
NHTSA – National Highway Traffic Safety Administration
NTSB – National Transportation Safety Board
OTS – California Office of Traffic Safety
SFDPH – San Francisco Department of Public Health
SFMTA – San Francisco Municipal Transportation Agency
SFPD – San Francisco Police Department
SDOT – Seattle Department of Transportation
SHSP – California Strategic Highway Safety Plan
SWITRS – Statewide Integrated Traffic Records System
TISS – Transportation-related Injury Surveillance System
UC ITS – University of California Institute for Transportation Studies