HomeMy WebLinkAboutItem 12 - COUNCIL READING FILE_f_Traffic Analysis Report
GHD | 669 Pacific St, Suite A, San Luis Obispo, CA 93401 | 11211884 | 11211884-TIAR001Final.docx | March 2021
Downtown Auto Lane
Reduction Study
Traffic Analysis Report
City of San Luis Obispo
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page i
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page i
Table of Contents
1. Introduction ................................................................................................................................... 1
2. Executive Summary ..................................................................................................................... 3
Vehicle Miles Travelled ...................................................................................................... 4
Existing Conditions (Pre-Covid)......................................................................................... 4
Existing Plus Project (Lane Reduction) ............................................................................. 4
Cumulative ......................................................................................................................... 6
Cumulative Plus Project (Lane Reduction) ........................................................................ 7
3. Analysis Methodology and Parameters...................................................................................... 10
3.1 Study Intersections & Segments ...................................................................................... 10
3.2 Data Collection and Analysis Time Periods ..................................................................... 10
3.3 Traffic Forecasts .............................................................................................................. 11
3.4 CEQA & City Level of Service Policy ............................................................................... 11
3.5 Level of Service Methodologies ....................................................................................... 12
3.6 Alternative Bicycle Phasing Scenarios ............................................................................ 13
3.6.1 Bicycle Scramble Phase ................................................................................. 13
3.6.2 Alternative Protected Bike Signal Scenario .................................................... 13
3.7 Significance and Mitigation Thresholds ........................................................................... 14
3.7.1 Intersection Level of Service Thresholds ....................................................... 14
3.7.1.1 Agency Intersection Level of Service Guidelines and Polices ....................... 14
3.7.2 LOS Thresholds Based on AADT ................................................................... 14
3.7.3 Vehicle Queue Standards ............................................................................... 15
3.8 Technical Analysis Parameters ....................................................................................... 15
4. Existing Conditions ..................................................................................................................... 16
4.1 Existing Intersection Operations ...................................................................................... 16
4.2 Existing Roadway Operations .......................................................................................... 17
4.3 Existing - Queue Operations ............................................................................................ 17
5. Project Description ..................................................................................................................... 19
5.1 Project Proposal ............................................................................................................... 19
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6. Existing Plus Project Conditions ................................................................................................ 19
6.1 Existing Intersection Operations ...................................................................................... 20
6.2 Existing Plus Project Roadway Operations ..................................................................... 20
6.3 Existing plus Project - Queue Operations ........................................................................ 21
6.4 Existing Plus Project w/ Bicycle Scramble Phase ........................................................... 22
6.5 Existing Plus Project w/ Bicycle Scramble Phase – Queue Operations ......................... 23
6.6 Existing Plus Project w/ Alternative Protected Bike Signal .............................................. 23
6.7 Existing Plus Project w/ Alternative Protected Bike Signal – Queue Operations ............ 23
7. Year 2040 Conditions ................................................................................................................. 25
7.1 Year 2040 No Project Conditions .................................................................................... 25
7.2 Year 2040 No Project Roadway Operations .................................................................... 26
7.3 Year 2040 No Project - Queue Operations ...................................................................... 26
8. Year 2040 Plus Project Conditions ............................................................................................ 28
8.1 Year 2040 Plus Project Conditions .................................................................................. 28
8.2 Year 2040 Plus Project Roadway Operations ................................................................. 29
8.3 Year 2040 Plus Project - Queue Operations ................................................................... 29
8.4 Year 2040 Plus Project w/ Bicycle Scramble Phase ....................................................... 31
8.5 Year 2040 Plus Project w/ Bicycle Scramble Phase – Queue Operations ..................... 31
8.6 Year 2040 Plus Project w/ Alternative Protected Bike Signal .......................................... 32
8.7 Year 2040 Plus Project w/ Alternative Protected Bike Signal – Queue Operations ....... 32
9. Overall Findings ......................................................................................................................... 33
Table Index
Table 3.1: Study Roadway Segments .................................................................................................. 10
Table 3.2: Study Roadway Segments .................................................................................................. 10
Table 3.3: LOS Criteria ......................................................................................................................... 12
Table 3.4: MMLOS Objectives and Service Standards ........................................................................ 14
Table 3.5: LOS AADT Thresholds ........................................................................................................ 14
Table 3.6: LOS AADT Thresholds ........................................................................................................ 15
Table 3.7: MMLOS Objectives and Service Standards ........................................................................ 15
Table 4.1: Existing Intersection Level of Service ................................................................................. 16
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Table 4.2: Existing Roadway Level of Service ..................................................................................... 17
Table 4.3: Existing Conditions Queuing Analysis ................................................................................. 17
Table 6.1: Existing Plus Project Intersection Level of Service ............................................................. 20
Table 6.2: Existing Roadway Level of Service ..................................................................................... 20
Table 6.3: Existing plus Project Conditions .......................................................................................... 21
Queuing Analysis ................................................................................................................ 21
Table 6.4: Existing Plus Project w/Bicycle Scramble Phase ................................................................ 22
Table 6.5: Existing Plus Project ............................................................................................................ 23
w/Bicycle Scramble Phase .................................................................................................. 23
Table 6.6: Existing Plus Project w/ Alternative Protected Bike Signal ................................................. 23
Table 6.7: Existing Plus Project ............................................................................................................ 24
w/Alternative Bicycle Protected Phase ................................................................................ 24
Table 7.1: Year 2040 No Project Conditions Level of Service ............................................................. 25
Table 7.2: Year 2040 No Project Conditions Roadway Level of Service ............................................. 26
Table 7.3: Year 2040 No Project Conditions ........................................................................................ 26
Queuing Analysis ................................................................................................................ 26
Table 8.1: Year 2040 Plus Project Conditions Level of Service ........................................................... 28
Table 8.2: Year 2040 Plus Project Conditions Roadway Level of Service ........................................... 29
Table 8.3: Year 2040 Plus Project Conditions ..................................................................................... 29
Queuing Analysis ................................................................................................................ 29
Table 8.4: Year 2040 Plus Project w/Bicycle Scramble Phase ............................................................ 31
Table 8.5: Year 2040 Plus Project ........................................................................................................ 31
w/Bicycle Scramble Phase .................................................................................................. 31
Table 8.6: Year 2040 Plus Project w/ Alternative Protected Bike Signal ............................................. 32
Table 8.7: Year 2040 Plus Project w/ Alternative Protected Bike Signal ............................................. 32
Appendix Index
Appendix A NACTO – Signal Phasing Strategy
Appendix B Synchro LOS Worksheets
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1. Introduction
The City of San Luis Obispo is proposing to remove one automobile lane on both Marsh & Higuera
Streets in the downtown core to address speeding, provide width for improved pedestrian & bicycle
facilities, as well as existing and future parklets. The overall scope of this project is depicted below.
Visual Simulations of the Proposed Changes are also provided below.
Higuera South of Nipomo
Existing Proposed
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Higuera at Court Street
Existing Proposed
Marsh Between Chorro & Morro
Existing Proposed
Marsh at Torro
Existing Proposed
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The purpose of this study is to analyze the operational affects of reducing travel lanes as proposed
on Marsh & Higuera within the Downtown Core following the City’s adopted level of service and
queue threshold policies. This Analysis has been conducted per the City’s RFP and traffic impact
study guidelines for 14 intersections and 12 segments within the scope of the proposed project
under existing and cumulative conditions. For the purposes of this analysis Higuera & Marsh are
considered East & West streets.
In addition, an assessment of a Bicycle scramble and a Bicycle Protected intersection phasing were
conducted at Marsh & Higuera as well as Marsh & Johnson under the existing + project &
cumulative + project scenarios.
This memorandum includes analysis scenarios as described below, using the City’s master synchro
network and most recent existing traffic volumes, GHD isolated the study area, validated and
updated geometry, volumes, and signal timing to existing conditions to establish the existing
conditions baseline conditions. GHD forecasted Existing + Project volumes based on a combination
of the City’s Traffic Model and most recent traffic volumes. For cumulative conditions GHD
forecasted Cumulative and Cumulative + Project volumes based on a combination of the City’s
Traffic Model and professional judgement.
This analysis assesses the following four scenarios:
• Existing Conditions
• Existing Plus Project Conditions
• Year 2040 No Project Conditions
• Year 2040 Plus Project Conditions
2. Executive Summary
Reduction of travel lanes as proposed would not cause level of service in the downtown to exceed
policy thresholds or create intersection queueing issues under current conditions. Under cumulative
conditions the downtown core is forecasted to have queues at Marsh & Higuera side streets that
exceed block lengths with and without the proposed project.
A Bicycle Scramble under current conditions at Marsh & Higuera & Marsh & Johnson would operate
within City level of Service policy thresholds, however queuing at Higuera & Marsh would exceed
capacity. Under Cumulative conditions Higuera & Marsh would exceed level of service thresholds
and queuing capacity whereas Marsh & Johnson would operate within level of service thresholds.
A Protected bicycle phase under current conditions at Marsh & Higuera & Marsh & Johnson would
operate within City level of Service policy thresholds. Under Cumulative conditions Higuera & Marsh
would exceed level of service thresholds and queuing capacity whereas Marsh & Johnson would
operate within level of service thresholds.
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Vehicle Miles Travelled
The proposed project satisfies California Office of Planning and Research screening criteria for
project type. “Projects that would not likely lead to a substantial or measurable increase in vehicle
travel, and therefore generally should not require and induced travel analysis, include: Reduction of
through lanes”
Existing Conditions (Pre-Covid)
• All intersections and segments meet LOS thresholds.
• Higuera Street & Marsh Street Intersection EBR turning movement (from Hwy 101 to SB
Higuera) in the AM and PM peaks exceed turn pocket capacity. However, the right turn
turning movement is consolidated with the eastbound thru movements, EBR turns do not
occlude or impact overall approach operations.
• Higuera Street & Nipomo Street Intersection NWL bound turning movements (NB Nipomo
to WB Higuera) in the PM exceeds turn pocket capacity. However, average queue is
calculated at 52 feet, only two feet over the current capacity. Effectively the current capacity
is fully utilized.
Existing Plus Project (Lane Reduction)
1. All intersections and segments meet LOS thresholds. The proposed project does not cause
level of service thresholds to be exceeded.
2. Higuera Street & Marsh Street EBR turning movements in the AM and PM exceed turn
pocket capacity. However, the right turn turning movement is consolidated with the
eastbound thru movements, EBR turns do not occlude or impact overall approach
operations.
3. Higuera Street & Nipomo Street Due to forecasted volume redistributions the proposed
project is forecasted to reduce NWL queuing at this intersection.
4. Forecasted volume and corridor capacities for both Marsh & Higuera are shown in the
figures below. Overall capacities are reduced with the lane reduction, however existing
volumes are still well within those capacities:
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Cumulative
1. All intersections and segments meet LOS thresholds.
2. Higuera Street & Marsh Street EBR (from Hwy 101 to SB Higuera) and NBL (From NB
Higuera to Hwy 101) turning movements in the AM and PM peak hour exceeds turn pocket
capacity.
The EBR turn turning movement is consolidated with the eastbound thru movements, EBR
turns do not occlude or impact overall approach operations.
The NBL (From NB Higuera to Hwy 101) queues are projected to exceed pocket capacity,
extending approximately 489 feet which is south of Pacific Street. However, Intersection
Widening and upgrades to roundabout control are identified in the City’s concept plans.
Recommendation: Prioritize future funding allocations for Higuera & Marsh Intersection
Upgrades.
3. Higuera Street & Nipomo Street NWL bound (NB Nipomo to WB Higuera) turning
movements in the AM and PM exceeds turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current left turn pocket is approximately 50’, under cumulative
conditions Nipomo left turn queues are forecasted to extend into the prior intersection at
Pacific.
Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
4. Marsh Street & Nipomo Street SEL bound (From SB Nipomo to EB Marsh) turning
movement in the AM peak hour exceeds turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current left turn pocket is approximately 50’, under cumulative
conditions Nipomo left turn queues are forecasted to extended into prior intersection at
Higuera.
Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
5. Marsh Street & Broad Street NWR bound (From NB Broad to EB Marsh) turning
movements in the AM peak hour exceed turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current right turn pocket is approximately 50’, under cumulative
conditions Broad right turn queues are forecasted to extended into prior intersection at
Pacific.
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Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
6. Higuera Street & Chorro Street SBR bound (From SB Chorro to WB Higuera) turning
movements in the AM and PM peak hour exceed turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current right turn pocket is approximately 50’, under cumulative
conditions Chorro right turn queues are forecasted to extended into prior intersection at
Monterey.
Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
Cumulative Plus Project (Lane Reduction)
7. All intersection and segments meet LOS thresholds.
8. Higuera Street & Marsh Street EBR (from Hwy 101 to SB Higuera) and NBL (From NB
Higuera to Hwy 101) turning movements in the AM and PM peak hour exceeds turn pocket
capacity. However, Intersection Widening and upgrades to roundabout control are identified
in the City’s concept plans.
The EBR turn turning movement is consolidated with the eastbound thru movements, EBR
turns do not occlude or impact overall approach operations.
The NBL (From NB Higuera to Hwy 101) queues are projected to exceed pocket capacity,
extending approximately 501 feet which is south of Pacific Street.
Recommendation: Prioritize future funding allocations for Higuera & Marsh Intersection
Upgrades.
9. Higuera Street & Nipomo Street NWL bound (NB Nipomo to WB Higuera) turning
movements in the AM and PM exceeds turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current left turn pocket is approximately 50’, under cumulative
conditions Nipomo left turn queues are forecasted to extend into the prior intersection at
Pacific.
Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
10. Marsh Street & Nipomo Street SEL bound (From SB Nipomo to EB Marsh) turning
movement in the AM peak hour exceeds turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current left turn pocket is approximately 50’, under cumulative
conditions Nipomo left turn queues are forecasted to extended into prior intersection at
Higuera.
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Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
11. Marsh Street & Broad Street NWR bound (From NB Broad to EB Marsh) turning
movements in the AM peak hour exceed turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current right turn pocket is approximately 50’, under cumulative
conditions Broad right turn queues are forecasted to extended into prior intersection at
Pacific.
Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
12. Higuera Street & Chorro Street SBR bound (From SB Chorror to WB Higuera) turning
movements in the AM and PM peak hour exceed turn pocket capacity.
Due to the closely spaced intersections in the downtown area, overall block lengths are
approximately 250’. The current right turn pocket is approximately 50’, under cumulative
conditions Chorro right turn queues are forecasted to extended into prior intersection at
Monterey.
Recommendation: Consider future parking removal for installation of TWLTL and upgrading
signal controls in the downtown core to an adaptive system.
5. Forecasted volume and corridor capacities for both Marsh & Higuera are shown in the
figures below. Overall capacities are reduced with the lane reduction, however future
volumes are still well within those capacities:
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3. Analysis Methodology and Parameters
3.1 Study Intersections & Segments
The following 14 intersections and 12 roadway segments were established were analyzed under
existing and cumulative conditions.
Study Intersections:
Table 3.1: Study Roadway Segments
# Intersection # Intersection
1. Higuera Street / Marsh Street 8. Marsh Street / Osos Street
2. Higuera Street / Nipomo Street 9. Marsh Street / Chorro Street
3. Marsh Street / Nipomo Street 10. Marsh Street / Johnson Street
4. Marsh Street / Broad Street 11. Higuera Street / Morro Street
5. Higuera Street / Broad Street 12. Marsh Street / Morro Street
6. Higuera Street / Chorro Street 13. Higuera Street / Santa Rosa Street
7. Higuera Street / Osos Street 14. Marsh Street / Santa Rosa Street
Roadway Segments:
Table 3.2: Study Roadway Segments
# Segment Limits
1. Higuera Street Marsh Street to Nipomo Street
2. Higuera Street Nipomo Street to Broad Street
3. Higuera Street Broad Street to Chorro Street
4. Higuera Street Chorro Street to Osos Street
5. Higuera Street Osos Street to Santa Rosa Street
6. Higuera Street Santa Rosa Street Toro Street
7. Higuera Street Toro Street to Johnson Street
8. Marsh Street Higuera Street to Nipomo Street
9. Marsh Street Nipomo Street to Broad Street
10. Marsh Street Broad Street to Osos Street
11. Marsh Street Osos Street to Santa Rosa Street
12. Marsh Street Santa Rosa Street to Johnson Street
3.2 Data Collection and Analysis Time Periods
Traffic volume trends have been affected by COVID to some degree, the extent to which is
temporary and permanent as part of a “new normal” is unknown. GHD used historical Weekday AM
and PM peak hour counts conducted by Quality Traffic Data in October 2018.
All intersections have been analyzed during the AM and PM peak hour periods. The AM peak hour
is defined as the highest continuous hour of peak traffic flow counted between 7:00 a.m. and 9:00
a.m. and the PM peak hour is defined as the highest continuous hour of peak traffic flow counted
between 3:00 p.m. and 6:00 p.m. under typical weekday conditions.
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3.3 Traffic Forecasts
Existing + Project volumes were forecasted using the City’s TransCAD travel demand model, lane
reductions were programmed in the base year scenario. Base Year and Base Year + Project
volumes were compared to determine proportional volume redistributions that could be expected as
a result of the lane reductions. Those proportional changes were then applied to existing volume to
determine forecasted Existing + Project Average Daily Segment and Peak Hour Intersection
Turning movement volumes.
Cumulative and Cumulative + Project volumes were also forecasted using the City’s TransCAD
travel demand model, lane reductions were programmed into the cumulative year scenario. Volume
for both scenarios were extracted from the model reviewed and validated for relative accuracy.
3.4 CEQA & City Level of Service Policy
Due to the nature of the project and California Office of Planning & Research Guidance the project
is presumed to have a less than significant impact on VMT, safety, & Induced Travel. The project is
also consistent with the City’s adopted withy City Adopted Transportation Plan & Policy and
therefore would be exempt of Environmental Review.
The City has however adopted Level of Service and Queueing policy thresholds outside of CEQA
which are primary focus of this transportation analysis.
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3.5 Level of Service Methodologies
The following section outlines the methodology and analysis parameters that were used to quantify
Existing and Year 2040 traffic operations at study intersections.
Table 3.3: LOS Criteria
Level of
Service
Type
of Flow Delay Maneuverability
Stopped Delay/Vehicle
Signalized
Un-
signalized
All-Way
Stop
A Stable Flow Very slight delay. Progression is
very favorable, with most vehicles
arriving during the green phase not
stopping at all.
Turning movements are
easily made, and nearly all
drivers find freedom of
operation.
<10.0 <10.0 <10.0
B Stable Flow Good progression and/or short cycle
lengths. More vehicles stop than for
LOS A, causing higher levels of
average delay.
Vehicle platoons are
formed. Many drivers begin
to feel somewhat restricted
within groups of vehicles.
>10.0 >10.0 >10.0
and and and
<20.0 <15.0 <15.0
C Stable Flow Higher delays resulting from fair
progression and/or longer cycle
lengths. Individual cycle failures
may begin to appear at this level.
The number of vehicles stopping is
significant, although many still pass
through the intersection without
stopping.
Back-ups may develop
behind turning vehicles.
Most drivers feel somewhat
restricted
>20.0 >15.0 >15.0
and and and
<35.0 <25.0 <25.0
D Approaching Unstable Flow The influence of congestion
becomes more noticeable. Longer
delays may result from some
combination of unfavorable
progression, long cycle lengths, or
high volume-to-capacity ratios.
Many vehicles stop, and the
proportion of vehicles not stopping
declines. Individual cycle failures
are noticeable.
Maneuverability is severely
limited during short periods
due to temporary back-ups.
>35.0 >25.0 >25.0
and and and
<55.0 <35.0 <35.0
E Unstable Flow Generally considered to be the limit
of acceptable delay. Indicative of
poor progression, long cycle
lengths, and high volume-to-
capacity ratios. Individual cycle
failures are frequent occurrences.
There are typically long
queues of vehicles waiting
upstream of the
intersection.
>55.0 >35.0 >35.0
and and and
<80.0 <50.0 <50.0
F Forced Flow Generally considered to be
unacceptable to most drivers. Often
occurs with over saturation. May
also occur at high volume-to-
capacity ratios. There are many
individual cycle failures. Poor
progression and long cycle lengths
may also be major contributing
factors.
Jammed conditions. Back-
ups from other locations
restrict or prevent
movement. Volumes may
vary widely, depending
principally on the
downstream back-up
conditions.
>80.0 >50.0 >50.0
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Due to the signal phasing, the intersections of Higuera Street & Marsh Street and Marsh Street &
Johnson Street was analyzed using the 2000 HCM methodology as the HCM 6 methodology does
not support the intersection phasing.
For signalized intersections, the intersection delays are average values for all intersection
movements. Table 3.3 (above) presents the delay-based LOS criteria for different types of
intersection control.
3.6 Alternative Bicycle Phasing Scenarios
An additional consideration is the addition of a bicycle scramble phase and alternative protected
bike signal scenario to the following signalized intersections for plus project scenarios only:
• Higuera Street & Marsh Street
• Marsh Street & Johnson Street
The above intersections were modified/analyzed to include a protected bicycle phase allowing
bicycle movement through the intersection. Analysis was conducted using Synchro 10.0
(Trafficware). As noted in Section 3.3, the intersections of Higuera Street & Marsh Street and
Marsh Street & Johnson Street was analyzed using the 2000 HCM methodology as the HCM 6
methodology does not support the intersection phasing.
3.6.1 Bicycle Scramble Phase
Bicycle Scramble Scenario phase incorporates a dedicated bicycle phase into the intersection
signal plan. Phase would prohibit turning movements for all other phases allowing for only thru
movement thru the intersection for bikes only.
3.6.2 Alternative Protected Bike Signal Scenario
As cited in NACTO (National Association of City
Transportation Officials), a protected bike signal is
a fully separated signal phasing for bikes. For the
protected intersection scenario, right turn on red
(RTOR) is prohibited. Refer to Appendix A.
NACTO
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3.7 Significance and Mitigation Thresholds
The following thresholds of significance or deficiencies were used to determine if the impact is
projected to have a significant impact and requires mitigation or operates below the City’s level of
service policy on study intersections and roadway segments.
3.7.1 Intersection Level of Service Thresholds
Under Senate Bill 743, automobile level of service is no longer considered an environmental impact.
However, the City of San Luis Obispo's General Plan Circulation Element contains the following
policy pertaining to LOS standards in the City. Because these level of service thresholds are no
longer subject to CEQA, deficiencies are not considered an environmental impact. Rather
inconsistency with local level of service policy should be addressed with conditions approval outside
of CEQA.
3.7.1.1 Agency Intersection Level of Service Guidelines and Polices
Section 6.1.2: Establish the following peak-hour LOS standards for multimodal objectives, service
standards, and significance criteria. They reflect the special circumstances of various areas of the
community. Table 3.4 identifies the LOS objectives and minimum LOS standards.
Table 3.4: MMLOS Objectives and Service Standards
Travel Mode LOS Objective Minimum LOS Standard
Bicycle B D
Pedestrian B C
Transit C Baseline LOS or LOS D, whichever is lower
Vehicle C E (Downtown), D (All Other Routes)
The City of San Luis Obispo's General Plan Circulation Element is accessible via the following
internet site: https://www.slocity.org/home/showdocument?id=6637.
3.7.2 LOS Thresholds Based on AADT
The following AADT thresholds of significance were estimated using the City of San Luis Obispo’s
General Plan Circulation Element methodologies based on Urban (>5,000 Population) Interrupted
Flow Arterial (Signalized) roadways as listed in Table 3.5 below.
Table 3.5: LOS AADT Thresholds
Urban (>5,000 Population) Interrupted Flow
Arterial (Signalized)
Lanes Divided
Level of Service
A B C D E
2 Undivided 0 3,200 10,480 12,400 13,040
2 Undivided 0 4,000 13,100 15,500 16,300
2 Divided 0 4,200 13,755 16,275 17,115
4 Undivided 3,450 20,925 24,600 25,650 25,650
4 Undivided 4,370 26,505 31,160 32,490 32,490
4 Divided 4,600 27,900 32,800 34,200 34,200
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Urban (>5,000 Population) Interrupted Flow
Arterial (Signalized)
Lanes Divided
Level of Service
A B C D E
6 Undivided 5,175 32,100 36,975 38,550 38,550
6 Undivided 6,555 40,660 46,835 48,830 48,830
6 Divided 6,900 42,800 49,300 51,400 51,400
For purposes of this study and existing study roadway segment one-way orientation, Table 3.5
above, highlighted in red, is modified below to represent one-way orientation thresholds.
Modification thresholds shown in Table 3.6 are half the values highlighted in red.
Table 3.6: LOS AADT Thresholds
Urban (>5,000 Population) Interrupted Flow
Arterial (Signalized)
Lanes Divided
Level of Service
A B C D E
1 Undivided 0 2,100 6,878 8,138 8,558
2 Undivided 2,300 13,950 16,400 17,100 17,100
3 Undivided 3,450 21,400 24,650 25,700 25,700
3.7.3 Vehicle Queue Standards
Vehicle queues are considered acceptable within this report if the queues are accommodated within
the available storage for left- and right turn lanes. Queues are based on Synchro que length (95th)
percentile and queues values were rounded to the nearest 25th foot (in the queue table analysis) as
the default value for passenger cars, for queue value outputs less than 25 feet.
3.8 Technical Analysis Parameters
This TAR provides an evaluation of traffic operating conditions by incorporating appropriate heavy
vehicle adjustment factors and peak hour factors. The resulting intersection delays and LOS are
estimated using HCM 6 based analysis methodologies.
Table 3.7 presents various parameters that are be applied to study intersections within this analysis.
Table 3.7: MMLOS Objectives and Service Standards
Technical Parameters City Intersections
Grade Level
% Trucks From Traffic Counts
PHF for Existing & Existing Plus Project From Traffic Counts
PHF for Future Conditions 0.92 of higher
The Synchro 10 (Trafficware) software suite will be used to implement the HCM 6 analysis
methodologies.
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4. Existing Conditions
The Existing conditions scenario represent current study intersections and traffic volumes are
analyzed and establishes the baseline traffic performance.
4.1 Existing Intersection Operations
Table 4.1 summarizes the intersection performance during the AM and PM peak hour at Existing
Conditions.
Table 4.1: Existing Intersection Level of Service
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 16.1 B -19.2 B -
2 Higuera St / Nipomo St Signal E 14.9 B -14.9 B -
3 Marsh St / Nipomo St Signal E 12.1 B -12.7 B -
4 Marsh St / Broad St Signal E 15.4 B -15.8 B -
5 Higuera St / Broad St Signal E 15.7 B -16.2 B -
6 Higuera St / Chorro St Signal E 10.9 B -11.6 B -
7 Higuera St / Osos St Signal E 8.9 A -9.0 A -
8 Marsh St / Osos St Signal E 9.6 A -9.9 A -
9 Marsh St / Chorro St Signal E 16.9 B -17.3 B -
10 Marsh St / Johnson St Signal E 48.8 D -37.3 D -
11 Higuera St to Morro St Signal E 18.6 B -18.6 B -
12 Marsh St / Morro St Signal E 11.0 B -11.7 B -
13 Higuera St / Santa Rosa St Signal E 8.2 A -9.2 A -
14 Marsh St / Santa Rosa St Signal E 13.2 B -13.7 B -
Notes:1. LOS = Delay based on average of all approaches for AWSC, Signal, RNDBT
2. Bold = Unacceptable Conditions
3. OVR = Delay over 300 seconds
Intersection
Control
Type1,2
Target
LOS
PM Peak HourAM Peak Hour
#
As presented in Table 4.1, all study intersections are currently found to operate at or above the
target threshold LOS.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 17
4.2 Existing Roadway Operations
Table 4.2 presents roadway facility characteristics and a summary of the Existing Plus Project
segment operations.
Table 4.2: Existing Roadway Level of Service
#Segment Limits Divided Direction
# of
Lanes AADT LOS
1 Higuera Street Marsh Street to Nipomo Street Undivided West 2 10,561 B
2 Higuera Street Nipomo Street to Broad Street Undivided West 3 9,384 B
3 Higuera Street Broad Street to Chorro Street Undivided West 3 11,858 B
4 Higuera Street Chorro Street to Osos Street Undivided West 3 10,112 B
5 Higuera Street Osos Street to Santa Rosa Street Undivided West 3 8,841 B
6 Higuera Street Santa Rosa Street Toro Street Undivided West 3 5,069 B
7 Higuera Street Toro Street to Johnson Street Undivided West 2 4,321 B
8 Marsh Street Higuera Street to Nipomo Street Undivided East 3 10,878 B
9 Marsh Street Nipomo Street to Broad Street Undivided East 3 9,578 B
10 Marsh Street Broad Street to Osos Street Undivided East 3 10,823 B
11 Marsh Street Osos Street to Santa Rosa Street Undivided East 3 8,825 B
12 Marsh Street Santa Rosa Street to Johnson StreetUndivided East 3 4,463 B
Urban (>5000 Population) Interupted Flow Arterial (Signalized)Exiting Segment AADT Volumes (2019)
As presented in Table 4.2, the study roadway segments is currently operating at acceptable LOS.
4.3 Existing - Queue Operations
Existing intersection queuing analysis focuses on the locations where queuing is most likely to
occur along the study intersections. Table 4.3 presents the 95th percentile queuing analysis for the
weekday AM and PM peak hours at the study intersections. Approach orientation description was
listed as coded in the Synchro file provided by the City.
Table 4.3: Existing Conditions Queuing Analysis
Existing Conditions - Queuing Analysis (95th %)
AM
Peak
PM
Peak
Storage
Capacity
84 Higuera St / Marsh St EBR 117 104 50
NBL 153 222 250
NBR 56 61 -
SBL -
SBR 42 75 -
89 Higuera St / Nipomo St
SER 25 27 65
NWL 41 52 50
SWL 25 25 440
SWR 440
90 Marsh St / Nipomo St
SEL 25 25 40
NWR -
NEL +1000
NER +1000
96 Marsh St / Broad St
SEL 25 25 45
NWR 25 36 90
NEL 440
NER 440
97 Higuera St / Broad St
SER 25 25 70
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 18
NWL -
SWL 615
SWR 615
99 Higuera St / Chorro St
NBL 25 25 50
SBR 25 25 65
SWL 430
SWR 430
102 Higuera St / Osos St
WBL 495
WBR 495
SER -
NWL -
103 Marsh St / Osos St
SEL 25 25 -
NWR 33 43 100
NEL 340
NER 340
115 Marsh St / Chorro St
NBR 25 25 75
SBL 52 56 75
NEL 600
NER 600
124 Marsh St / Johnson St
SEL 25 25 75
NWR 75
NEL 88 154 +1000
NER 42 39 +1000
SWL 151 132 +1000
SWR 100
134 Higuera St to Morro St
WBL 335
WBR 335
NBL -
SBR 25 25 75
135 Marsh St / Morro St
EBL 440
EBR 440
SEL -
NWR -
154 Higuera St / Santa Rosa St
WBL 550
WBR 550
NBL 25 25 100
SBR 34 35 -
155 Marsh St / Santa Rosa St
EBL 68 75 490
EBR 25 25 490
SEL 25 25 75
NWR -
Notes:
Bold = Overall Segment Length Bold = Exceeds Storage Capacity
As presented in Table 4.3 all the intersection queuing movements did not exceed the storage
capacity except for the following intersections:
• Higuera Street & Marsh Street in the AM and PM peak hour: Significant eastbound traffic
turning right movement exceeds the queue storage capacity. However, the right turn turning
movement is consolidated with the eastbound thru movements, EBR turns do not occlude
or impact overall approach operations.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 19
• Higuera Street & Nipomo Street in the PM peak hour: Northwest bound traffic turning left
exceeds the queue storage capacity by 2’, effectively utilizing the full capacity of the turning
movement.
Recommendations: Both intersections are at full queueing capacity, the City should actively
monitor these locations and optimize signal timing frequently.
5. Project Description
5.1 Project Proposal
Consistent with the Downtown Concept Plan, the paving project proposes removal of one auto
travel lane on Marsh and Higuera in order to reduce illegal speeding and provide more street width
for pedestrian and bicycle facilities, as well as existing and future parklets. These modifications
would retain sufficient traffic capacity to accommodate existing and future auto traffic volumes.
These plans would extend the current pilot lane reductions and bikeway enhancements on Higuera
Street (Santa Rosa to Nipomo) to a permanent configuration. Existing pilot parklet installations will
be retained and may become permanent pending City Council approval. Final designs will be
refined based on community input.
6. Existing Plus Project Conditions
The Existing Plus Project conditions presents traffic impacts after superimposing the additional
increment traffic generated by the proposed project onto Existing traffic volumes, intersection lane
geometrics, and controls. This scenario assumes no additional background development to occur
beyond the proposed project.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 20
6.1 Existing Intersection Operations
Table 6.1 presents a summary of the intersection operations for the weekday AM and PM peak hour
scenarios for the Existing Plus Project Scenarios.
Table 6.1: Existing Plus Project Intersection Level of Service
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 16.4 B -19.5 B -
2 Higuera St / Nipomo St Signal E 13.8 B -15.9 B -
3 Marsh St / Nipomo St Signal E 14.3 B -15.5 B -
4 Marsh St / Broad St Signal E 17.2 B -17.9 B -
5 Higuera St / Broad St Signal E 16.7 B -18.2 B -
6 Higuera St / Chorro St Signal E 9.5 A -13.0 B -
7 Higuera St / Osos St Signal E 10.2 B -10.1 B -
8 Marsh St / Osos St Signal E 4.2 A -11.5 B -
9 Marsh St / Chorro St Signal E 18.7 B -18.8 B -
10 Marsh St / Johnson St Signal E 55.2 E -41.7 D -
11 Higuera St to Morro St Signal E 20.5 C -21.1 C -
12 Marsh St / Morro St Signal E 12.3 B -13.6 B -
13 Higuera St / Santa Rosa St Signal E 56.1 E -20.9 C -
14 Marsh St / Santa Rosa St Signal E 13.9 B -17.4 B -
Notes:
2. Bold = Unacceptable Conditions
3. OVR = Delay over 300 seconds
1. LOS = Delay based on average of all approaches for AWSC, Signal, RNDBT
Intersection
Control
Type1,2
Target
LOS
PM Peak HourAM Peak Hour
#
As presented in Table 6.1, all study intersections are projected to operate at or above the target
threshold LOS.
6.2 Existing Plus Project Roadway Operations
Table 6.2 presents roadway facility characteristics and a summary of the Existing Plus Project
segment operations.
Table 6.2: Existing Roadway Level of Service
#Segment Limits Divided Direction
# of
Lanes AADT LOS
1 Higuera Street Marsh Street to Nipomo Street Undivided West 2 10,615 B
2 Higuera Street Nipomo Street to Broad Street Undivided West 2 9,064 B
3 Higuera Street Broad Street to Chorro Street Undivided West 2 10,864 B
4 Higuera Street Chorro Street to Osos Street Undivided West 2 8,947 B
5 Higuera Street Osos Street to Santa Rosa Street Undivided West 2 7,855 B
6 Higuera Street Santa Rosa Street Toro Street Undivided West 2 5,386 B
7 Higuera Street Toro Street to Johnson Street Undivided West 1 4,462 B
8 Marsh Street Higuera Street to Nipomo Street Undivided East 2 10,527 B
9 Marsh Street Nipomo Street to Broad Street Undivided East 2 9,178 B
10 Marsh Street Broad Street to Osos Street Undivided East 2 10,361 B
11 Marsh Street Osos Street to Santa Rosa Street Undivided East 2 8,864 B
12 Marsh Street Santa Rosa Street to Johnson StreetUndivided East 3 4,291 B
Urban (>5000 Population) Interupted Flow Arterial (Signalized)Exiting plus Project Segment AADT Volumes (2019)
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 21
As presented in Table 6.2, the study roadway segments are projected to operate at acceptable
LOS.
6.3 Existing plus Project - Queue Operations
Existing plus Project intersection queuing analysis focuses on the locations where queuing is most
likely to occur along the study intersections. Table 6.3 presents the 95th percentile queuing analysis
for the weekday AM and PM peak hours at the study intersections. Approach orientation description
was listed as coded in the Synchro file provided by the City.
Table 6.3: Existing plus Project Conditions
Queuing Analysis
Existing + Project - Queuing Analysis (95th %)
AM
Peak
PM
Peak
Storage
Capacity
84 Higuera St / Marsh St EBR 121 103 50
NBL 155 221 250
NBR 55 61 -
SBL -
SBR 42 75 -
89 Higuera St / Nipomo St
SER 25 28 65
NWL 35 41 50
SWL 440
SWR 440
90 Marsh St / Nipomo St
SEL 25 25 40
NWR -
NEL +1000
NER +1000
96 Marsh St / Broad St
SEL 25 27 45
NWR 25 28 90
NEL 440
NER 440
97 Higuera St / Broad St
SER 25 25 70
NWL -
SWL 615
SWR 615
99 Higuera St / Chorro St
NBL 25 48 50
SBR 25 25 65
SWL 430
SWR 430
102 Higuera St / Osos St
WBL 495
WBR 495
SER -
NWL -
103 Marsh St / Osos St
SEL 25 25 -
NWR 26 44 100
NEL 340
NER 340
115 Marsh St / Chorro St
NBR 25 25 75
SBL 55 57 75
NEL 600
NER 600
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 22
124 Marsh St / Johnson St
SEL 25 25 75
NWR 75
NEL 88 154 +1000
NER 43 40 +1000
SWL 171 160 +1000
SWR 100
134 Higuera St to Morro St
WBL 335
WBR 335
NBL -
SBR 25 75
135 Marsh St / Morro St
EBL 440
EBR 440
SEL -
NWR -
154 Higuera St / Santa Rosa St
WBL 550
WBR 550
NBL 27 31 100
SBR 45 37
155 Marsh St / Santa Rosa St
EBL 490
EBR 490
SEL 25 25 75
NWR -
Notes:
Bold = Overall Segment Length
Bold = Exceeds Storage Capacity
As presented in Table 6.3 all the intersection queuing movements did not exceed the storage
capacity except for the following intersection:
6. Higuera Street & Marsh Street in the AM and PM peak hour: Significant eastbound traffic
turning right movement exceeds the queue storage capacity. However, the right turn turning
movement is consolidated with the eastbound thru movements, EBR turns do not occlude
or impact overall approach operations.
Recommendations: This intersection is at full queueing capacity; the City should actively
monitor these locations and optimize signal timing frequently.
6.4 Existing Plus Project w/ Bicycle Scramble Phase
Table 6.4 presents a summary of the intersection operations for the weekday AM and PM peak hour
scenarios for the Existing Plus Project w/Bicycle Scramble Phase Scenario.
Table 6.4: Existing Plus Project w/Bicycle Scramble Phase
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 35.5 D -73.9 E -
10 Marsh St / Johnson St Signal E 63.2 E -44.3 D -
#Intersection
Control
Type1,2
Target
LOS
AM Peak Hour PM Peak Hour
As presented in Table 6.4, both study intersections are projected to operate at or above the target
threshold LOS.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 23
6.5 Existing Plus Project w/ Bicycle Scramble Phase –
Queue Operations
Table 6.5 presents the 95th percentile queuing analysis for the weekday AM and PM peak hours at
the study intersections for Existing Plus Project w/ Bicycle Scramble Phase. Approach orientation
description was listed as coded in the Synchro file provided by the City.
Table 6.5: Existing Plus Project
w/Bicycle Scramble Phase
Existing + Project (w/bicycle phase) - Queuing Analysis (95th %)
AM
Peak
PM
Peak Storage Capacity
84 Higuera St / Marsh St EBR 209 146 50
NBL2 223 286 250
NBR -
SBL -
SBR 262 849 -
124 Marsh St / Johnson St
SEL2 25 25 75
NWR 34 75
NEL 80 141 +1000
NER2 41 36 +1000
SWL 157 148 +1000
SWR 100
Notes:
Bold = Overall Segment Length
Bold = Exceeds Storage Capacity
As presented in Table 6.5, only Higuera Street & Marsh Street in both the AM and PM peak hour
exceed storage capacity. The intersection had significant eastbound traffic turning right in the AM
and PM peak hour and just slightly northbound traffic turning left in the PM peak hour.
6.6 Existing Plus Project w/ Alternative Protected Bike Signal
Table 6.6 presents a summary of the intersection operations for the weekday AM and PM peak hour
scenarios for the Existing Plus Project w/Alternative Protected Bike Signal Scenario.
Table 6.6: Existing Plus Project w/ Alternative Protected Bike Signal
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 19.5 B -31.4 C -
10 Marsh St / Johnson St Signal E 56.7 E -42.2 D -
#Intersection
Control
Type1,2
Target
LOS
AM Peak Hour PM Peak Hour
As presented in Table 6.6, both study intersections are projected to operate at or above the target
threshold LOS.
6.7 Existing Plus Project w/ Alternative Protected Bike Signal –
Queue Operations
Table 6.7 presents the 95th percentile queuing analysis for the weekday AM and PM peak hours at
the study intersections for Existing Plus Project w/ Alternative Protected Bike Signal. Approach
orientation description was listed as coded in the Synchro file provided by the City.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 24
Table 6.7: Existing Plus Project
w/Alternative Bicycle Protected Phase
Existing + Project (w/bicycle phase) - Queuing Analysis (95th %)
AM
Peak
PM
Peak Storage Capacity
84 Higuera St / Marsh St EBR 226 208 50
NBL 170 238 250
NBR 251 -
SBL -
SBR 172 666 -
124 Marsh St / Johnson St
SEL 25 25 75
NWR 37 75
NEL 88 154 +1000
NER 264 179 +1000
SWL 171 160 +1000
SWR 50 100
Notes:
Bold = Overall Segment Length
Bold = Exceeds Storage Capacity
As presented in Table 6.7, only Higuera Street & Marsh Street in both the AM and PM peak hour
exceed storage capacity. However, the right turn turning movement is consolidated with the
eastbound thru movements, EBR turns do not occlude or impact overall approach operations.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 25
7. Year 2040 Conditions
Year 2040 conditions refer to an analysis scenario approximately 20 years in the future. For
cumulative conditions GHD forecasted Cumulative and Cumulative + Project volumes based on a
combination of the City’s Traffic Model and professional judgement.
7.1 Year 2040 No Project Conditions
Table 7.1 summarizes the intersection performance during the AM and PM peak hour for projected
Year 2040 No Project Conditions.
Table 7.1: Year 2040 No Project Conditions Level of Service
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 33.0 C -44.9 D -
2 Higuera St / Nipomo St Signal E 16.0 B -18.2 B -
3 Marsh St / Nipomo St Signal E 14.0 B -13.9 B -
4 Marsh St / Broad St Signal E 17.6 B -18.3 B -
5 Higuera St / Broad St Signal E 18.4 B -21.4 C -
6 Higuera St / Chorro St Signal E 13.5 B -15.4 B -
7 Higuera St / Osos St Signal E 12.1 B -11.8 B -
8 Marsh St / Osos St Signal E 3.6 A -3.8 A -
9 Marsh St / Chorro St Signal E 3.5 A -3.1 A -
10 Marsh St / Johnson St Signal E 17.5 B -26.7 C -
11 Higuera St to Morro St Signal E 19.1 B -20.8 C -
12 Marsh St / Morro St Signal E 13.0 B -13.9 B -
13 Higuera St / Santa Rosa St Signal E 12.1 B -11.6 B -
14 Marsh St / Santa Rosa St Signal E 14.5 B -15.1 B -
Notes:1. LOS = Delay based on average of all approaches for AWSC, Signal, RNDBT
2. Bold = Unacceptable Conditions
3. OVR = Delay over 300 seconds
Intersection
Control
Type1,2
Target
LOS
PM Peak HourAM Peak Hour
#
As presented in Table 7.1, all study intersections are expected to operate at or above the threshold
LOS.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 26
7.2 Year 2040 No Project Roadway Operations
Table 7.2 presents roadway facility characteristics and a summary of the Year 2040 No Project
segment operations.
Table 7.2: Year 2040 No Project Conditions Roadway Level of Service
#Segment Limits Divided Direction
# of
Lanes AADT LOS
1 Higuera Street Marsh Street to Nipomo Street Undivided West 2 14,799 C
2 Higuera Street Nipomo Street to Broad Street Undivided West 3 12,982 B
3 Higuera Street Broad Street to Chorro Street Undivided West 3 14,164 C
4 Higuera Street Chorro Street to Osos Street Undivided West 3 12,795 B
5 Higuera Street Osos Street to Santa Rosa Street Undivided West 3 10,759 B
6 Higuera Street Santa Rosa Street Toro Street Undivided West 3 7,227 B
7 Higuera Street Toro Street to Johnson Street Undivided West 2 5,259 B
8 Marsh Street Higuera Street to Nipomo Street Undivided East 3 14,721 C
9 Marsh Street Nipomo Street to Broad Street Undivided East 3 13,141 B
10 Marsh Street Broad Street to Osos Street Undivided East 3 14,003 C
11 Marsh Street Osos Street to Santa Rosa Street Undivided East 3 10,854 B
12 Marsh Street Santa Rosa Street to Johnson Street Undivided East 3 6,902 B
Cumulative Base AADT Volumes (2040)
As presented in Table 7.2, the study roadway segments are projected to operate at acceptable
LOS.
7.3 Year 2040 No Project - Queue Operations
Year 2040 No Project intersection queuing analysis focuses on the locations where queuing is most
likely to occur along the study intersections. Table 7.3 presents the 95th percentile queuing analysis
for the weekday AM and PM peak hours at the study intersections. Approach orientation description
was listed as coded in the Synchro file provided by the City.
Table 7.3: Year 2040 No Project Conditions
Queuing Analysis
Cumulative Conditions - Queuing Analysis (95th %)
AM
Peak
PM
Peak
Storage
Capacity
84 Higuera St / Marsh St EBR 462 173 50
NBL 262 489 250
NBR 212 214 -
SBL -
SBR 65 173 -
89 Higuera St / Nipomo St
SER 25 29 65
NWL 129 177 50
SWL 25 25 440
SWR 440
90 Marsh St / Nipomo St
SEL 58 86 40
NWR -
NEL +1000
NER +1000
96 Marsh St / Broad St
SEL 25 25 45
NWR 92 77 90
NEL 440
NER 440
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 27
97 Higuera St / Broad St
SER 25 31 70
NWL -
SWL 615
SWR 615
99 Higuera St / Chorro St
NBL 25 25 50
SBR 87 94 65
SWL 430
SWR 430
102 Higuera St / Osos St
WBL 495
WBR 495
SER -
NWL -
103 Marsh St / Osos St
SEL 33 33 -
NWR 64 72 100
NEL 340
NER 340
115 Marsh St / Chorro St
NBR 47 37 75
SBL 66 33 75
NEL 600
NER 600
124 Marsh St / Johnson St
SEL 25 25 75
NWR 75
NEL 89 201 +1000
NER 34 59 +1000
SWL 33 35 +1000
SWR 100
134 Higuera St to Morro St
WBL 335
WBR 335
NBL -
SBR 49 52 75
135 Marsh St / Morro St
EBL 440
EBR 440
SEL -
NWR -
154 Higuera St / Santa Rosa St
WBL 550
WBR 550
NBL 25 25 100
SBR 159 193 -
155 Marsh St / Santa Rosa St
EBL 81 72 490
EBR 25 25 490
SEL 25 25 75
NWR -
Notes:
Bold = Overall Segment Length
Bold = Exceeds Storage Capacity
As presented in Table 7.3 all the intersection queuing movements did not exceed the storage
capacity except for the following intersections:
• Higuera Street & Marsh Street in the AM and PM peak hour: Significant eastbound traffic
turning right movement exceeds the queue storage capacity. Additionally, substantial
northbound traffic turning left movement also exceeds the queue storage capacity.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 28
• Higuera Street & Nipomo Street in the AM and PM peak hour: Significant northwest bound
traffic turning left movement exceeds the queue storage capacity.
• Marsh Street & Nipomo Street in the AM peak hour: Southeast bound traffic turning left
exceeds the queue storage capacity.
• Marsh Street & Broad Street in the AM peak hour: Northwest bound traffic turning right
narrowly exceeds the queue storage capacity.
• Higuera Street & Chorro Street in the AM and PM peak hour: Significant southbound traffic
turning right movement exceeds the queue storage capacity.
Recommendation: Consider future parking removal on side streets for installation of TWLTL and
upgrading signal controls in the downtown core to an adaptive system.
8. Year 2040 Plus Project Conditions
Year 2040 Plus Project conditions refer to an analysis scenario approximately 20 years in the future
with project. Cumulative Plus Project volumes based on a combination of the City’s Traffic Model
and professional judgement.
8.1 Year 2040 Plus Project Conditions
Table 8.1 summarizes the intersection performance during the AM and PM peak hour for projected
Year 2040 Plus Project Conditions.
Table 8.1: Year 2040 Plus Project Conditions Level of Service
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 33.1 C -45.2 D -
2 Higuera St / Nipomo St Signal E 15.9 B -19.3 B -
3 Marsh St / Nipomo St Signal E 13.6 B -14.8 B -
4 Marsh St / Broad St Signal E 19.7 B -23.1 C -
5 Higuera St / Broad St Signal E 18.0 B -24.6 C -
6 Higuera St / Chorro St Signal E 14.8 B -20.5 C -
7 Higuera St / Osos St Signal E 15.7 B -14.8 B -
8 Marsh St / Osos St Signal E 6.0 A -3.9 A -
9 Marsh St / Chorro St Signal E 3.6 A -4.7 A -
10 Marsh St / Johnson St Signal E 17.8 B -26.2 C -
11 Higuera St to Morro St Signal E 19.7 B -23.6 C -
12 Marsh St / Morro St Signal E 15.4 B -19.2 B -
13 Higuera St / Santa Rosa St Signal E 40.9 D -11.4 B -
14 Marsh St / Santa Rosa St Signal E 13.6 B -16.5 B -
Notes:
3. OVR = Delay over 300 seconds
Intersection
Control
Type1,2
Target
LOS
PM Peak HourAM Peak Hour
#
1. LOS = Delay based on average of all approaches for AWSC, Signal, RNDBT
2. Bold = Unacceptable Conditions
As presented in Table 8.1, all study intersections are projected to operate at or above the target
LOS threshold.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 29
8.2 Year 2040 Plus Project Roadway Operations
Table 8.2 presents roadway facility characteristics and a summary of the Year 2040 Plus Project
segment operations.
Table 8.2: Year 2040 Plus Project Conditions Roadway Level of Service
#Segment Limits Divided Direction
# of
Lanes AADT LOS
1 Higuera Street Marsh Street to Nipomo Street Undivided West 2 14,607 C
2 Higuera Street Nipomo Street to Broad Street Undivided West 2 11,770 B
3 Higuera Street Broad Street to Chorro Street Undivided West 2 12,194 B
4 Higuera Street Chorro Street to Osos Street Undivided West 2 11,258 B
5 Higuera Street Osos Street to Santa Rosa Street Undivided West 2 9,330 B
6 Higuera Street Santa Rosa Street Toro Street Undivided West 2 6,986 B
7 Higuera Street Toro Street to Johnson Street Undivided West 1 4,935 B
8 Marsh Street Higuera Street to Nipomo Street Undivided East 2 13,834 B
9 Marsh Street Nipomo Street to Broad Street Undivided East 2 12,540 B
10 Marsh Street Broad Street to Osos Street Undivided East 2 12,673 B
11 Marsh Street Osos Street to Santa Rosa Street Undivided East 2 9,592 B
12 Marsh Street Santa Rosa Street to Johnson Street Undivided East 3 6,478 B
Cumulative Base plus Project AADT Volumes (2040)
As presented in Table 8.2, the study roadway segment is projected to operate at acceptable LOS.
8.3 Year 2040 Plus Project - Queue Operations
Year 2040 Plus Project intersection queuing analysis focuses on the locations where queuing is
most likely to occur along the study intersections. Table 8.3 presents the 95th percentile queuing
analysis for the weekday AM and PM peak hours at the study intersections. Approach orientation
description was listed as coded in the Synchro file provided by the City.
Table 8.3: Year 2040 Plus Project Conditions
Queuing Analysis
Cumulative + Project - Queuing Analysis (95th %)
AM
Peak
PM
Peak
Storage
Capacity
84 Higuera St / Marsh St EBR 471 175 50
NBL 263 501 250
NBR 203 215 -
SBL -
SBR 65 169 -
89 Higuera St / Nipomo St
SER 25 32 65
NWL 134 208 50
SWL 23 25 440
SWR 440
90 Marsh St / Nipomo St
SEL 53 83 40
NWR -
NEL 195 175 200
NER +1000
96 Marsh St / Broad St
SEL 25 25 45
NWR 94 66 90
NEL 440
NER 440
97 Higuera St / Broad St
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 30
SER 25 32 70
NWL -
SWL 126 105 200
SWR 615
99 Higuera St / Chorro St
NBL 25 25 50
SBR 73 98 65
SWL 430
SWR 430
102 Higuera St / Osos St
WBL 495
WBR 495
SER -
NWL -
103 Marsh St / Osos St
SEL 25 25 -
NWR 27 74 100
NEL 340
NER 340
115 Marsh St / Chorro St
NBR 46 49 75
SBL 72 40 75
NEL 600
NER 600
124 Marsh St / Johnson St
SEL 75
NWR 75
NEL 88 198 +1000
NER 34 59 +1000
SWL 33 36 +1000
SWR 100
134 Higuera St to Morro St
WBL 25 25 200
WBR 25 25 200
NBL -
SBR 35 54 75
135 Marsh St / Morro St
EBL 440
EBR 440
SEL -
NWR -
154 Higuera St / Santa Rosa St
WBL 550
WBR 550
NBL 30 25 100
SBR -
155 Marsh St / Santa Rosa St
EBL 490
EBR 490
SEL 25 25 75
NWR -
Notes:
Bold = Overall Segment Length
Bold = Exceeds Storage Capacity
Bold = Lane Improvement
As presented in Table 8.3 all the intersection queuing movements did not exceed the storage
capacity except for the following intersections:
• Higuera Street & Marsh Street in the AM and PM peak hour: Substantial eastbound traffic
turning right movement exceeds the queue storage capacity. Additionally, substantial
northbound traffic turning left movement also exceeds the queue storage capacity.
GHD | Downtown Lane Reduction: Traffic Analysis Report | 11221884-TIAR001Final | Page 31
• Higuera Street & Nipomo Street in the AM and PM peak hour: Significant northwest bound
traffic turning left movement exceeds the queue storage capacity.
• Marsh Street & Nipomo Street in the AM and PM peak hour: Considerable southeast bound
traffic turning left movement exceeds the queue storage capacity.
• Marsh Street & Broad Street in the AM and PM peak hour: Considerable northwest bound
traffic turning right movement narrowly exceeds the queue storage capacity.
• Higuera Street & Chorro Street in the AM and PM peak hour: Significant southbound traffic
turning right movement exceeds the queue storage capacity.
Recommendation: Consider future parking removal on side streets for installation of TWLTL and
upgrading signal controls in the downtown core to an adaptive system.
8.4 Year 2040 Plus Project w/ Bicycle Scramble Phase
Table 8.4 presents a summary of the intersection operations for the weekday AM and PM peak hour
scenarios for the Year 2040 Plus Project w/Bicycle Scramble Phase Scenario.
Table 8.4: Year 2040 Plus Project w/Bicycle Scramble Phase
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 71.2 E -139.1 F -
10 Marsh St / Johnson St Signal E 35.2 D -28.3 C -
#Intersection
Control
Type1,2
Target
LOS
AM Peak Hour PM Peak Hour
As presented in Table 8.4, only the intersection of Marsh Street & Johnson Street is projected to
operate at or above the target threshold LOS. The intersection of Higuera Street & Marsh Street in
the PM peak hour is projected to experience LOS F, not operating at or above the target threshold.
8.5 Year 2040 Plus Project w/ Bicycle Scramble Phase –
Queue Operations
Table 8.5 presents the 95th percentile queuing analysis for the weekday AM and PM peak hours at
the study intersections for Year 2040 Plus Project w/ Bicycle Scramble Phase. Approach orientation
description was listed as coded in the Synchro file provided by the City.
Table 8.5: Year 2040 Plus Project
w/Bicycle Scramble Phase
Cum + Project (w/bicycle phase) - Queuing Analysis (95th %)
AM
Peak
PM
Peak Storage Capacity
84 Higuera St / Marsh St EBR 668 212 50
NBL2 328 650 250
NBR 169 185 -
SBL -
SBR 489 1036 -
124 Marsh St / Johnson St
SEL2 75
NWR 75
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NEL 121 184 +1000
NER2 25 57 +1000
SWL 40 35 +1000
SWR 100
Notes:
Bold = Overall Segment Length
Bold = Exceeds Storage Capacity
As presented in Table 8.5, Higuera Street & Marsh Street in the AM and PM peak exceeds the
storage capacity. There is substantial eastbound traffic movement turning right and significant
northbound traffic movement turning left, exceeding the queue storage capacity.
Recommendation: A Bicycle Scramble Phase at Marsh & Higuera locations is not recommended
under cumulative conditions without other significant intersection and corridor improvements.
8.6 Year 2040 Plus Project w/ Alternative Protected Bike Signal
Table 8.6 presents a summary of the intersection operations for the weekday AM and PM peak hour
scenarios for the Year 2040 Plus Project w/ Alternative Protected Bike Signal Scenario.
Table 8.6: Year 2040 Plus Project w/ Alternative Protected Bike Signal
Delay LOS
Warrant
Met?3 Delay LOS
Warrant
Met?3
1 Higuera St / Marsh St Signal E 80.1 F -123.3 F -
10 Marsh St / Johnson St Signal E 17.8 B -26.8 C -
#Intersection
Control
Type1,2
Target
LOS
AM Peak Hour PM Peak Hour
As presented in Table 8.6, only the intersection of Marsh Street & Johnson Street is projected to
operate at or above the target threshold LOS. The intersection of Higuera Street & Marsh Street in
the AM and PM peak hour is projected to experience LOS F, operating below the target threshold.
8.7 Year 2040 Plus Project w/ Alternative Protected Bike Signal –
Queue Operations
Table 8.7 presents the 95th percentile queuing analysis for the weekday AM and PM peak hours at
the study intersections for Year 2040 Plus Project w/ Alternative Protected Bike Signal Scenario.
Approach orientation description was listed as coded in the Synchro file provided by the City.
Table 8.7: Year 2040 Plus Project w/
Alternative Protected Bike Signal
Cum + Project (w/bicycle phase) - Queuing Analysis (95th %)
AM
Peak
PM
Peak Storage Capacity
84 Higuera St / Marsh St EBR 734 271 50
NBL 263 501 250
NBR 812 831 -
SBL -
SBR 334 806 -
124 Marsh St / Johnson St
SEL2 75
NWR 75
NEL 121 198 +1000
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NER 84 212 +1000
SWL 33 36 +1000
SWR 49 100
Notes:
Bold = Overall Segment Length
Bold = Exceeds Storage Capacity
As presented in Table 8.7, Higuera Street & Marsh Street in the AM and PM peak exceeds the
storage capacity. There is substantial eastbound traffic movement turning right and significant
northbound traffic movement turning left, exceeding the queue storage capacity. However, this
would only occur during bicycle activations.
Recommendation: With conditional bike phase programming these intersections would function
adequately during cycles without bicycle activation. However, during phases with Bicycle Activation
Higuera & Marsh would operate below City level of Service Thresholds and queueing would exceed
capacities.
9. Overall Findings
The proposed lane reductions in the Downtown Core would not cause congestions levels to exceed
City level of service thresholds under both current and future conditions. Higuera & Marsh and
Marsh & Nipomo are currently at queueing capacity for particular movements with or without the
proposed land reduction.
In general, downtown queueing under cumulative conditions is projected to exceed block lengths on
most side street approaches to the Higuera & Marsh segments. This will occur with or without the
proposed project. There are limited solutions given the short block lengths; some options the City
may consider is future on-street parking removal for the installation of Two-Way Left Turn Lanes or
upgrading to an adaptive signal system in the downtown core.
A bicycle scramble operation would operate within level of service thresholds at both locations
under current conditions. However, a bicycle scramble at Marsh & Higuera would exceed level of
service thresholds at some point between now and projected buildout of the City. Therefore, a
bicycle scramble is not recommended at Marsh & Higuera without other significant intersection or
corridor improvements. The City’s Mid-Higuera and downtown concept plans contemplates
widening and roundabout controls at Higuera & Marsh, including Class I circulating lanes around
such a roundabout would be an effective solution for this location.
Protected Bicycle Phasing operation would also operate within level of service thresholds at both
locations under current conditions. However, protected bicycle phasing at Marsh & Higuera would
also exceed level of service thresholds at some point between now and projected buildout of the
City. Therefore, protected bicycle phasing is not recommended at Marsh & Higuera without other
significant intersection or corridor improvements. The City’s Mid-Higuera and downtown concept
plans contemplates widening and roundabout controls at Higuera & Marsh, including Class I
circulating lanes around such a roundabout would be an effective solution for this location.
Downtown Auto Lane Reduction Traffic Analysis Report | 11221884-TIAR001Final |