Aaron M. Cox, PE, TE, PMP
Principal Engineer
August 19, 2026
• 6 Lane Major Arterial Roadway, 46,000 Veh/day
• Closely spaced intersections
• Businesses on both sides of roadway
• Full access to businesses from Magnolia Ave.
• Adjacent to Caltrans traffic signals serving the I-15 • Corridor serves businesses, schools, and commuter
traffic
Magnolia Ave.
Rimpau Ave. El Sobrante Rd. SB I-15 Off Ramp
Corona Marketplace Shopping Center
360’ 150’
2 • Difficult to coordinate City and Caltrans signals with closely spaced intersections
• Built to ultimate right-of-way, widening not feasible • Competing objectives:
• Caltrans traffic signal prioritizes I-15 ramp
• City intersections prioritize Magnolia Ave.
Magnolia Ave.
Corona Marketplace Shopping Center
360’ 150’
3 Rimpau Ave. El Sobrante Rd. SB I-15 Off Ramp
• Traffic congestion blocking intersection
• Aggressive queue cutting
• Impulsive lane changes and weaving
• Traffic cut through of businesses
• Ignoring traffic signals and signs
• Increased acceleration for yellow/red lights
Magnolia
Ave.
El Sobrante Rd.
Corona Marketplace Shopping Center
Southbound facing camera in northeast corner
SB I-15 Ramp
4 Spring 2025 Spring 2025 Summer 2026 Fall 2026
West leg crosswalk removal
improved signal coordination
on Magnolia Ave.
Crosswalk Removal
Magnolia Ave. corridor signal timing
was updated to better coordinate
with Caltrans operations at the time
of implementation
Signal Timing Changes
Signal timing will
respond to dynamic
demands
“AI”
Implementation
Analyzed existing signal operations
and proposed alternatives to help
alleviate congestion
Traffic Study
5 These improvements have optimized operations with the existing roadway geometry 6 • Signal timing has already been analyzed and optimized • Crosswalk removal reduced delay as a cause of signal timing transitions • El Sobrante Rd. timing is very short to maintain Magnolia Ave. coordination with Caltrans signals • Adaptive ("AI") control can make small improvements when there are deviations in traffic conditions
• Closely spaced intersections limit further improvement • Roadway geometry is the remaining constraint
Study the corridor with a review of existing
conditions and analyze various alternatives
to alleviate congestion on Magnolia Ave. at
the El Sobrante Rd. signalized intersection.
Provide details on impacts to motorists and
businesses.
7 Legend:
Project Study
Intersection
Additional
Intersections
Studied
8 9
The study evaluated:
Overall Delay
Queues
Traffic redistribution
Safety
Corridor operations
Business access
No Build Right-In/RightOut at
El Sobrante Rd.
No Access from
El Sobrante Rd.
to Magnolia Ave.
A B C
Remove Traffic Signal at El
Sobrante Rd.
Convert El Sobrante Rd. to
right-in/right-out only
Convert Corona Marketplace
Shopping Center to
right-in/right only out at
Magnolia Ave.
No changes to vehicle
movements
Maintain recently
implemented Magnolia Ave
signal timing
Remove Traffic Signal at El
Sobrante Rd.
Convert El Sobrante Rd. to
right-in only
Convert Corona Marketplace
Shopping Center to
right-in/right only out at
Magnolia Ave.
10 Alternative
No Build (Existing Conditions)
A
11 Alternative A:
Intersection Delay
One location has less than
acceptable Level of Service
(LOS) today:
1. Rimpau Ave. at Corona
Marketplace Shopping
Center S. Driveway in
both AM and PM peak
hour conditions
12 AM Peak Hour PM Peak Hour
Intersection sec LOS sec LOS
1. Rimpau Ave. and Sixth St. 19.1 B 27.9 C
2. Rimpau Ave. and Circle City Dr. 33.8 D 25.5 D
3. Rimpau Ave. and Corona Marketplace N. Driveway 13.8 B 15.4 C
4. Rimpau Ave. and Corona Marketplace S. Driveway 38.1 E 70.6 F
5. El Sobrante Rd. and Sixth St. 19.0 B 27.6 C
6. El Sobrante Rd. and Circle City Dr. 10.0 A 10.9 B
7. Radio Rd and Sixth St. 19.4 B 24.4 C
8. El Camino Ave. and Sixth St. 19.7 B 15.8 B
9. El Camino Ave. and Corona Pointe Ct. 12.3 B 16.2 C
10. El Camino Ave. and Carly Wy. 6.7 A 7.5 A
11. El Camino Ave. and Magnolia Ave. 20.7 C 19.6 B
12. I-15 NB Ramps and Magnolia Ave. 28.5 C 47.7 D
13. I-15 SB Ramps and Magnolia Ave. 31.1 C 29.1 C
14. El Sobrante Rd. and Magnolia Ave. 29.6 C 19.2 B
15. Rimpau Ave. and Magnolia Ave. 29.6 C 31.8 C
Alternative A: Maintain recently implemented signal timing changes with no changes to vehicle movements
13 Vehicle Queuing
Observed queue lengths exceeded available
pocket storage length, causing vehicle spillback
Rimpau Ave. Magnolia Ave. El Sobrante Rd. SB I-15 Off Ramp Corona Marketplace Shopping Center
AM
PM
Alternative
Removal of Traffic Signal & Convert to
Right-In/Right-Out Movements at
El Sobrante Rd.
B
14 Convert El Sobrante Rd.
to right-in/right-out
Convert Marketplace
Shopping Center to
right-in/right out
Remove traffic signal at
Magnolia Ave. and
El Sobrante Rd.
Extend median and
striping into
intersection
Alternative B: 15
Rimpau Ave. El Sobrante Rd.
Corona Marketplace Shopping Center
Magnolia Ave.
Legend:
El Sobrante Rd./Magnolia Ave.
Intersections Studied
Magnolia Ave. Eastbound
Left Turn rerouted traffic
Alternative B: 16
Legend:
El Sobrante Rd./Magnolia Ave.
Intersections Studied
Magnolia Ave. Westbound Left
Turn rerouted traffic
Alternative B: 17
Legend:
El Sobrante Rd./Magnolia Ave.
Intersections Studied
El Sobrante Rd. Southbound
Left Turn rerouted Traffic
Alternative B: 18
19 AM Peak Hour PM Peak Hour
No Build Alt. B No Build Alt. B
Intersection Control Type LOS LOS LOS LOS
1. Rimpau Ave. and Sixth St. Signalized B B C C
2. Rimpau Ave. and Circle City Dr.
AWSC D E D D
Signalized D A D A
3. Rimpau Ave. and Corona Marketplace N. Driveway TWSC B B C C
4. Rimpau Ave. and Corona Marketplace S. Driveway
TWSC E E F F
Signalized E B F B
5. El Sobrante Rd. and Sixth St. Signalized B B C C
6. El Sobrante Rd. and Circle City Dr. TWSC A A B B
7. Radio Rd and Sixth St. Signalized B C C C
8. El Camino Ave. and Sixth St. Signalized B B B B
9. El Camino Ave. and Corona Pointe Ct. TWSC B C C C
10. El Camino Ave. and Carly Wy. Signalized A A A A
11. El Camino Ave. and Magnolia Ave. Signalized C C B C
12. I-15 NB Ramps and Magnolia Ave. Signalized C C D D
13. I-15 SB Ramps and Magnolia Ave. Signalized C D C D
14. El Sobrante Rd. and Magnolia Ave. TWSC C B B A
15. Rimpau Ave. and Magnolia Ave. Signalized C D C D
Signalizing Circle City Dr.
and Corona Marketplace S.
Driveway mitigates the
impacts of the
redistributed traffic.
Alternative B:
Decrease in Acceptable LOS
Decrease to Unacceptable LOS
Improvement in Acceptable LOS
No Change in Acceptable LOS
20 Vehicle Queuing
Queue slightly increased at
Rimpau Ave. and Magnolia Ave.
Rimpau Ave. Magnolia Ave. El Sobrante Rd. SB I-15 Off Ramp Corona Marketplace Shopping Center
Alternative B:
AM
PM
Corridor Benefits Localized Benefits
+ Reduces overall system delay of:
+ 43.2 Sec/Veh in the AM Peak Hour
+ 37.0 Sec/Veh in the PM Peak Hour
+ Reduces queue spillback to the SB I-15
ramp intersection
+ Increased corridor reliability (less volatile)
+ Increased safety
+ Rimpau Ave. / Corona Marketplace S.
Driveway improves LOS E/F to LOS A/A
+ Maintains signalized access to Corona
Marketplace Shopping Center from
Rimpau Ave.
+ Rimpau Ave./Circle City Dr. signalization
improves LOS D/D to LOS A/A
+ Reduced Shopping Center cut through
21 Alternative B: 21
Alternative
Removal of Traffic Signal & Convert to
Full Closure of El Sobrante Rd. Access to
Magnolia Ave.
C
22 Convert El Sobrante Rd. to
right-in ONLY(no access to
Magnolia Ave. from
El Sobrante Rd.)
Convert Marketplace
Shopping Center to right-in
/right out
Remove traffic signal at
Magnolia Ave. and
El Sobrante Rd.
Extend median and striping
into intersection
Alternative C: 23
Rimpau Ave. El Sobrante Rd.
Corona Marketplace Shopping Center
Magnolia Ave.
Legend:
El Sobrante Rd./Magnolia Ave.
Intersections Studied
Magnolia Ave. Eastbound
Left Turn rerouted traffic
Alternative C: 24
Legend:
El Sobrante Rd./Magnolia Ave.
Intersections Studied
Magnolia Ave. Westbound
Left Turn rerouted traffic
Alternative C: 25
Legend:
El Sobrante Rd./Magnolia Ave.
Intersections Studied
El Sobrante Rd. Southbound
Left and Right Turn Traffic
Alternative C: 26
27 AM Peak Hour PM Peak Hour
No Build Alt. B No Build Alt. B
Intersection Control Type LOS LOS LOS LOS
1. Rimpau Ave. and Sixth St. Signalized B C C D
2. Rimpau Ave. and Circle City Dr.
AWSC D F D F
Signalized D A D A
3. Rimpau Ave. and Corona Marketplace N. Driveway TWSC B B C C
4. Rimpau Ave. and Corona Marketplace S. Driveway
TWSC E E F F
Signalized E B F B
5. El Sobrante Rd. and Sixth St. Signalized B B C B
6. El Sobrante Rd. and Circle City Dr. TWSC A A B A
7. Radio Rd and Sixth St. Signalized B C C C
8. El Camino Ave. and Sixth St. Signalized B B B B
9. El Camino Ave. and Corona Pointe Ct. TWSC B C C C
10. El Camino Ave. and Carly Wy. Signalized A A A A
11. El Camino Ave. and Magnolia Ave. Signalized C C B C
12. I-15 NB Ramps and Magnolia Ave. Signalized C C D D
13. I-15 SB Ramps and Magnolia Ave. Signalized C D C D
14. El Sobrante Rd. and Magnolia Ave. TWSC C A B A
15. Rimpau Ave. and Magnolia Ave. Signalized C D C D
Signalizing Circle City Dr.
and Corona Marketplace S.
Driveway would mitigate the
impacts of the redistributed
traffic.
Alternative C:
Decrease in Acceptable LOS
Decrease to Unacceptable LOS
Improvement in Acceptable LOS
No Change in Acceptable LOS
Corridor Benefits Localized Benefits
+ Reduces overall system delay of:
+ 41.0 Sec/Veh in the AM Peak Hour
+ 29.0 Sec/Veh in the PM Peak Hour
+ Reduces queue spillback to the SB I-15
ramp intersection
+ Increased corridor reliability (less volatile)
+ Increased safety
+ Rimpau Ave. / Corona Marketplace S.
Driveway improves LOS E/F to LOS B/B
+ Signalized access to Corona Marketplace
Shopping Center from Rimpau Ave.
+ Rimpau Ave./Circle City Dr. signalization
improves LOS D/D to LOS A/A
Alternative C: 28
Comparison of
Alternatives
29 Overall
Delay
+ Significant delays + 43.2 s/veh. reduction (AM)
+ 37.0 s/veh. reduction (PM)
+ 41.0 s/veh. reduction (AM)
+ 29.0 s/veh. reduction (PM)
Safety
+ Status quo + Reduction in conflicting
movements improves safety,
weaving maneuvers, and
driving behavior
+ Reduction in conflicting
movements improves safety,
weaving maneuvers, and driving
behavior
Queue
+ 2 Locations exceed acceptable
queue lengths today
+ Slight increase of left turn
queue due to rerouted traffic
+ Accommodated in longer
storage pocket made possible
by signal removal
+ Slight increase of left turn queue
due to rerouted traffic
+ Accommodated in longer
storage pocket made possible
by signal removal
Access
+ Existing access preserved.
Brief signal timing to maintain
coordination may mean several
cycles to pass through
+ WB Magnolia Ave. reroute is
minor
+ EB Magnolia Ave. reroute is
moderate
+ WB Magnolia Ave. reroute is
minor
+ EB Magnolia Ave. reroute is
moderate
+ SB El Sobrante Rd. reroute is
significant
No Build Right-In/Right-Out
at El Sobrante Rd.
(Staff Recommendation)
No Access from
El Sobrante Rd. to A Magnolia Ave. B C
30 That the City Council Direct staff to either take no further action or advance the preferred Alternative into preliminary engineering and public outreach to refine the concept, evaluate implementation details, and return to Council with a recommended project scope, engineer's cost estimate, and implementation strategy for consideration as a future Capital Improvement Project.
31