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HomeMy WebLinkAbout11/4/2025 Item 6b, Collins and Horn - Staff Agenda CorrespondenceCity of San Luis Obispo, Council Memorandum City of San Luis Obispo Council Agenda Correspondence DATE: November 4, 2025 TO: Mayor and Council FROM: Scott Collins, Assistant City Manager Prepared By: Matt Horn, Major City Projects Manager VIA: Whitney McDonald, City Manager SUBJECT: ITEM #6b - PRADO INTERCHANGE AND BRIDGE VALUE ENGINEERING Staff received the following questions, regarding the Prado Interchange Project. The questions are below with staff’s response shown in italics : 1) Why does Prado Road remain four lanes between the overpass and Higuera if the overpass is two lanes? The traffic sensitivity analysis (October 2025) evaluated both 2 -lane and 4-lane bridge configurations. It found that a 2-lane overcrossing would still require four lanes east of the ramps to Higuera because reducing lanes in that section caused “significant congestion and delays” and was therefore dropped from consideration. This is due to the heavy westbound PM peak-hour demand (1,600–1,900 vehicles) between the northbound ramps, Elks Lane, and Higuera Street —queueing extended through multiple intersections in modeling scenarios. In short, even if the overpass narrows to two lanes to reduce bridge costs, the approaches must expand back to four lanes east of the ramps to maintain acceptable intersection operations and prevent backups into US 101. This expansion from 2 to 4 lanes at the approaches is cost neutral as this is the current design included the Preferred Alternative. 2) Why does the Prado Creek Bridge need to accommodate six lanes, and can that be revisited? The Bridge Project has been designed to accommodate forecasted traffic volumes consistent with the City’s General Plan Buildout, including the completion of both the Prado Road Interchange and Road Extension Projects. Item 6b - Prado Interchange and Bridge Value Engineering Page 2 The current project scope includes: replacement of the existing Prado Road Bridge over San Luis Obispo Creek; roadway improvements along Prado Road from the Water Resource Recovery Facility to Serra Meadows, installation of protected intersection improvements at Prado Road and Higuera Street ; and replacement and undergrounding of utilities within the project limits, including portions of Higuera Street. Specifically, the proposed Prado Road Bridge replacement is designed to provide the following features: • Four travel lanes • Two turn lanes • Two sidewalks • Two-direction protected bike lanes • Two on-street bike lanes • Removal and replacement of the existing Bob Jones Trail shared -use path bridge The estimated cost to construct all these improvements is $45.5 million. Opportunities to reduce overall project costs may be explored through value engineering, and a potential recommendation reflecting this approach is included in the Prado Interchange staff report as Alternative 3. 3) Why would the ATC alternatives (Figures 13 & 14) include both Class II and Class IV bike lanes? Figures 13 and 14 reflect staff’s interpretation of the Active Transportation Committee’s (ATC) recommendations in conjunction with Caltrans design requirements. Both figures correspond to Segment 1 as identified in the staff report and illustrate a roadway section that includes a Class II bike lane (roadway shoulder) and a Class IV separated bikeway. The Class II Lane is primarily intended for bicycle use, but may also be utilized by vehicles when necessary. The ATC expressed support for the inclusion of Class IV facilities, and as a result, both Figures 13 and 14 incorporate these lanes. Staff also supports maintaining the proposed shoulder width within Segment 1, as it enhances multimodal functionality and provides space for vehicles to safely pull out of the travel lane in the event of mechanical issues. This design approach helps maintain traffic flow through this constrained segment of Prado Road and reduces the potential for congestion. Since publishing of the staff report, we have received correspondence from several members of the ATC, clarifying the intent of their direction. This will be addressed through a separate agenda correspondence. Item 6b - Prado Interchange and Bridge Value Engineering Page 3 4) Were sidewalks on both sides of the street considered in any of the segments (1, 2, or 3) as an alternative to having both a bike lane and a separate multi-use path on the south side? Both the current Preferred Alternative shown in Figure 6 of the staff report and the Figure 14 Alternative include sidewalks on both sides of Prado Road, designated exclusively for pedestrian use, throughout all three segments. 5) On California Blvd, at the end of the Pepper Street Bike Bridge, the city used metal fencing as the separator between car traffic and the shared use path. Would this be a potential material, rather than the k -rail pictured in the plans, for the separator on the whole stretch of the shared use path in this project? Figures 8 and 9 of the staff report show a concrete K -rail serving as a barrier between the southerly shared-use path and the roadway. If the Council ultimately accepts staff’s recommendation to reduce the design speed on Prado Road from 45 mph to 35 mph, current shared-use path design standards would no longer require installation of a physical barrier. The Active Transportation Committee (ATC) expressed support through discussion (not a formal motion) to eliminate the barrier due to concerns that bicycle handlebars could come into contact with it. If the Council prefers to retain some form of separation, a metal fence could be considered as an alternative to the concrete K-rail. Below are two additional figures not included in the staff report that represent what Segment 1 and Segment 2 might look like using an elevated share use path along the south side of Prado Road and removing the barrier. Figure 15 – Segment 1 without barrier and with elevated shared -use path Item 6b - Prado Interchange and Bridge Value Engineering Page 4 Figure 16 – Segment 2 without barrier and with elevated shared -use path 6) With regard to the on-street-bike lanes, is there any buffer planned between the cars and the bike lane? There are currently no plans to install buffered bike lanes within Segments 1, 2, or 3. The staff report includes a rough order of magnitude cost estimate indicating that each additional foot of bridge width would cost approximately $500,000. If the Council wishes to provide a buffer between travel modes, this figure can be used as a general cost factor for evaluating potential modifications in Segments 1 and 2. Segment 3, however, presents additional challenges, as available space is constrained by the existing City right-of-way and the design interfaces with both Segment 2 and the Prado Creek Bridge. Segment 3 serves as the transition area between the Interchange Project and the Bridge Project. 7) The one-way bike lane for Segment 3 is elevated, almost to sidewalk level. However, this layout is not noted in any of the other segments. Would there be additional expense in elevating the one -way bike lanes in any of the sections to be more similar to th at proposed in Segment 3? Yes, elevated bike lanes in Segments 1 and 2 would result in additional costs. As noted in Question 3, the Class II bike lanes in these segments serve a dual purpose as both roadway shoulders and bicycle lanes. These shoulder/bike lane areas cannot be replaced by elevated facilities and therefore would require widening the bridge structure, which would increase overall project costs due to the additional bridge width required.