DATE: 08/19/2026
TO: Honorable Mayor and City Council Members
FROM: Public Works Department
2026-289
REQUEST FOR CITY COUNCIL ACTION
SUBJECT:
UPDATE ON OPTIONS FOR MAGNOLIA AVENUE AND EL SOBRANTE ROAD
CORRIDOR IMPROVEMENT
EXECUTIVE SUMMARY:
This staff report asks Council to consider three alternatives to improve traffic flow along the Magnolia Avenue corridor at El Sobrante Road, and to provide direction on whether to advance one of the concepts into preliminary engineering and to conduct public outreach.
RECOMMENDED ACTION:
That the City Council:
a. Adopt Alternative A – Take no further action
b. Adopt Alternative B – Right-In/Right-Out at El Sobrante Rd. (Staff Recommendation)
c. Adopt Alternative C – No Access from El Sobrante Rd. to Magnolia d. Provide staff with additional direction
BACKGROUND & HISTORY:
Magnolia Avenue is one of the City's principal east-west arterial roadways and serves regional traffic traveling between Interstate 15, commercial areas, residential neighborhoods, schools, and employment centers. The intersection of Magnolia Avenue and El Sobrante Road is located immediately east of the Interstate 15 southbound offramp and approximately 360 feet east of the signalized intersection at Rimpau Avenue.
Because of the close spacing between adjacent traffic signals and the operational interaction with the Caltrans-owned freeway ramp signals, traffic operations within this corridor are constrained by competing priorities. Caltrans prioritizes freeway ramp operations to minimize queue spillback onto Interstate 15, while the City prioritizes progression along Magnolia Avenue. The proximity of intersections limits the effectiveness of traditional traffic signal timing improvements.
In 2025, City Council directed staff to evaluate potential operational improvements beyond conventional signal timing adjustments. Since that time, the City has completed several improvements intended to optimize corridor operations, including:
Removal of the west leg crosswalk at El Sobrante Road; Updated corridor signal timing plans coordinated with Caltrans; Deployment of adaptive traffic signal technology capable of responding to changing traffic demands; and
Completion of a comprehensive corridor traffic operations study evaluating multiple access management alternatives.
Since Council first directed staff to study this corridor, additional engineering analysis was performed to evaluate the effects of redistributed traffic on adjacent intersections. This supplemental analysis included traffic counts at ten (10) additional intersections and evaluated whether localized improvements could offset the impacts associated with access modifications at El Sobrante Road. The results demonstrate that targeted improvements at nearby intersections substantially improve corridor-wide operations while preserving the benefits of the proposed access management strategy.
ANALYSIS:
The Public Works Department retained a traffic engineering consultant to evaluate operational improvements for the Magnolia Avenue corridor. The study evaluated fifteen (15) intersections throughout the surrounding roadway network during the weekday AM and PM peak hours.
The objective of the study was not simply to evaluate operations at El Sobrante Road, but to determine whether changes at that intersection would improve the performance of the Magnolia Avenue corridor as a whole. Accordingly, each alternative was evaluated based on its effect on:
Corridor delay
Queue lengths
Traffic redistribution
Access
Safety
Adjacent intersections
The traffic analysis included:
Existing and projected traffic operations
Level of Service (LOS)
Vehicle delay
Queue lengths and available storage
Traffic redistribution associated with each alternative Traffic signal timing optimization
Operational impacts throughout the surrounding roadway network Three alternatives were evaluated.
Alternative A – No Build
Alternative A maintains the existing roadway configuration while utilizing the recently implemented signal timing improvements.
This alternative maintains full access for all motorists and businesses but does not substantially improve congestion along Magnolia Avenue. Queue lengths are projected to continue increasing over time as traffic volumes grow, and closely spaced traffic signals continue to limit corridor progression.
Alternative B – Right-In/Right-Out Access
Alternative B converts El Sobrante Road and the Corona Marketplace driveway to rightin/right-out access while removing the traffic signal at El Sobrante Road.
Restricting left-turn movements allows Magnolia Avenue to operate as a continuous arterial by eliminating one closely spaced signalized intersection, reducing vehicle conflicts, improving progression, and decreasing the likelihood of queue spillback toward the Interstate 15 southbound ramps.
As expected, restricting left-turn access redistributes a portion of traffic to adjacent intersections, most notably:
Rimpau Avenue at Circle City Drive
Rimpau Avenue at the Corona Marketplace South Driveway Recognizing this redistribution, supplemental engineering analysis evaluated potential mitigation measures such as future signalized control. The analysis determined that signalization substantially improves operations and restores acceptable Levels of Service while accommodating the redistributed traffic. When these mitigation improvements are incorporated, Alternative B produces a net reduction in vehicle delay across the study corridor during both the AM and PM peak periods.
Alternative C – Limited Access
Alternative C removes direct access between El Sobrante Road and Magnolia Avenue while maintaining only right-in access from Magnolia Avenue.
Although this alternative provides operational benefits similar to Alternative B, it introduces greater impacts to local circulation and requires substantially longer detours for motorists accessing El Sobrante Road.
Staff finds these additional access restrictions outweigh the incremental operational benefit.
While Alternative B substantially improves corridor operations, it also requires more controlled access to adjacent businesses and redistributes certain turning movements to nearby intersections. These impacts can be mitigated through future intersection improvements, directional signing, and refinement during preliminary engineering. Staff concludes that these tradeoffs represent the most balanced solution among the alternatives evaluated.
Staff Recommendation:
Based on the completed engineering analysis, staff recommend Alternative B as the preferred corridor improvement strategy. Unlike the No Build alternative, Alternative B addresses the underlying geometric constraint created by closely spaced intersections rather than relying solely on signal timing improvements. Alternative B provides the best balance between improving traffic operations on Magnolia Avenue, maintaining reasonable access to adjacent properties, and minimizing impacts to the surrounding roadway network.
The supplemental analysis demonstrates that the operational impacts associated with redistributed traffic can be effectively mitigated through the future installation of traffic signals at:
Rimpau Avenue/Circle City Drive
Rimpau Avenue/Corona Marketplace south driveway
When evaluated as a comprehensive corridor improvement, Alternative B:
Improves progression along Magnolia Avenue;
Eliminates a closely spaced traffic signal;
Reduces conflict points and opportunities for intersection blocking; Reduces queue spillback risk near the Interstate 15 ramps; Produces a net reduction in overall vehicle delay throughout the study area; Maintains reasonable access to adjacent businesses through alternate routes.
Alternative C provides similar operational benefits on Magnolia Avenue but requires substantially greater traffic diversion and creates additional impacts to local circulation without providing meaningful operational advantages over Alternative B. For these reasons, staff does not recommend Alternative C.
Because the traffic study is a preplanning exercise, staff recommend that the preferred alternative be advanced into preliminary engineering and public outreach prior to establishing a Capital Improvement Project. This additional phase would refine the conceptual design, identify mitigation measures, develop preliminary cost estimates, conduct stakeholder outreach, and return to City Council with a refined implementation strategy.
FINANCIAL IMPACT:
If the City Council directs staff to proceed with preliminary engineering and public outreach, staff anticipates utilizing the City's existing on-call traffic engineering consultant to complete the work. The estimated cost for these services, including staff time, is approximately $30,000, which would include refinement of the conceptual design, development of preliminary traffic mitigation concepts, stakeholder and public outreach, evaluation of implementation details, and preparation of a planning-level engineer's cost estimate. Funding is available in the Public Works Department's operating budget within the Gas Tax Fund (FD_1222). Upon completion of the preliminary engineering effort, staff would return to the City Council with a refined project scope, implementation strategy, and funding recommendations for consideration as a future Capital Improvement Project.
ENVIRONMENTAL ANALYSIS:
This action is exempt pursuant to Section 15061(b)(3) of the Guidelines for the California Environmental Quality Act (CEQA), which states that a project is exempt from CEQA if the activity is covered by the general rule that CEQA applies only to projects that have the potential for causing a significant effect on the environment. Where it can be seen with certainty that there is no possibility that the activity in question may have a significant effect on the environment, the activity is not subject to CEQA. Selection of a preferred conceptual alternative does not constitute approval of a construction project. Any future implementation would undergo environmental review in accordance with the California Environmental Quality Act (CEQA) prior to final design and construction. Since there is no possibility that this action will have a significant effect on the environment, no environmental analysis is required.
PREPARED BY: AARON M. COX, PRINCIPAL ENGINEER
REVIEWED BY: JAVIER LUNA, ACTING PUBLIC WORKS DIRECTOR
ATTACHMENTS:
1. Exhibit 1 – Presentation
2. Exhibit 2 – Future Agenda Request Form (Speake)