Thank you for your request to improve the safety and efficiency of Alameda’s transportation system. It has been received as #20-02-0131. Public Works maintains 85 signalized intersections in Alameda. Depending on the nature of your request, our transportation engineer and/or our signal shop will respond within the next two weeks . If your request is an urgent matter, please call 747-7930 and describe the urgency.

Thank you for your request to improve traffic signals in Alameda. We appreciate your feedback regarding the need to give vehicles turning left protected movement without pedestrians crossing at the same time. As an organization, it is our commitment to prioritize safety for all users of the road through our General Plan, Vision Zero Policy, Active Transportation Plan, and an upcoming policy on standardizing traffic signal operations throughout the city. The City is working to improve traffic safety and operations throughout the city, especially for pedestrians and bicyclists.

While your service request did not state the intersection you are concerned about, the issue you are bringing up is an important one and I would like to explain it a bit further. Left turns represent one of the riskiest and most disruptive movements in the operation of a signalized intersection. As a result, safe and efficient left-turn operation is a critical component of any signalized intersection. The left-turn phasing operation can have a significant impact on the safety, level of delay, and throughput of an intersection.

Currently, left turn movements throughout the city are either protected-only or permissive-only. Permissive-only phasing allows two opposing approaches to run at the same time, with left turns allowed after vehicles yield to conflicting traffic and pedestrians. Protected-only phasing gives a separate phase for left-turning vehicles on a green left arrow signal indication only, with no pedestrian movement or vehicular traffic conflicting with the time given for left turns. Each operation has its own advantages and disadvantages. For the City to consider a change from one operation to another, the following factors need to be considered and evaluated by traffic/transportation engineers:
1. Current traffic volume count at the intersection
2. Sight Distance and related characteristics
3. Number of Left-turn Lanes and Intersection Geometry
4. Crossing Distance / Number of Opposing Lanes
5. Intersection and Receiving Facility Characteristics
6. Critical Crossing Gap
7. Correctable Left-Turn Crashes
8. Pedestrian Considerations
9. Corridor Consistency and Other Network Considerations
10. Funding needed for a signal modification to make the changes

Given the factors listed above, if an intersection warrants an operational change from a permissive-only to a protected-only left turn phasing, a signal modification to make it happen will be in order. Signal modifications may cost anywhere from about $30,000 to $200,000 depending on the age of the intersection including its current signal equipment within the controller cabinet, underground conduit sizing, detection system, and age of the mast arms and poles, the scale of the signal modification can be determined. Upon a signal modifications, the signal timing plans will also need to be updated and programmed into the controller.

At this time, the City is prioritizing safety projects aligned with our data-driven, Vision Zero Policy. The top three projects are:
1. Daylighting—with the goal to improve visibility at all intersections along our high injury corridors (design & implementation currently in progress).
2. School Safety—with the goal to improve safety at and near seven schools with Safe Routes 2 Schools recommendations (design currently in progress).
3. Intersection Safety—with the goal to evaluate and make improvements to the least safe intersections in Alameda. These are locations with the highest collisions on-record, that are large/skewed with sight-distance and operational issues. These intersections will require engineering analysis, design, construction, and additional funding to complete. (design to be scheduled).

Please see our website for more information:
https://www.alamedaca.gov/Departments/Planning-Building-and-Transportation/Transportation/Vision-Zero

With the Traffic Signal Operation Policy, which is currently in development, we will look at each corridor and intersection in the city and determine the best programming to fit the bike, pedestrian, and vehicle movements throughout the day. Evaluation for protected left-turn movements will also be included.

Again, thank you for your feedback and we look forward to implementing our Vision Zero improvements projects as well as a Traffic Signal Operations Policy to help us expeditiously bring intersection safety to all.

Regards,

Thank you for submitting this request (#20-02-0131). It has been addressed and is now closed.