On August 30th, the Sunnyvale City Council will select their preferred options for grade separations at Sunnyvale Ave and Mary Ave (see agenda and materials). Sunnyvale is considering lowering Sunnyvale Ave and Mary Ave underneath the Caltrain tracks – projects that together could cost up to $700 million. .
With electric service set to start in 2024, Caltrain is planning to provide more frequent service. This is providing more motivation to Sunnyvale and other cities planning to separate local streets from the Caltrain tracks to improve safety and reduce horn noise.
Sunnyvale Avenue Underpass
For the Sunnyvale Ave Underpass, there are two options:
- Bicycle and Pedestrian Only Undercrossing: This would allows bikes and pedestrians to cross and costs ~$100 million.
- Underpass Tunnel: ~$250 million tunnel that allows pedestrians cyclists, and vehicles to cross the tracks
In nearby Mountain View, that City faced with a similar choice, decided to close Castro Street to vehicles, add a ramp connecting to the existing Shoreline overpass, and build an underpass for pedestrians and cyclists.
In Sunnyvale, traffic studies showed that over 80% of drivers cross the tracks using the existing overpasses at Mathilda and Fair Oaks. Sunnyvale’s finding was similar to Mountain View, where studies showed that 90% of people accessed the downtown area by routes other than the Castro at-grade crossing of the Caltrain tracks,
Sunnyvale Ave | Mathilda | Fair Oaks | Percent Using Overpass | |
Peak hour trips | 1500 | 4700 | 3000 | 84% |
Daily trips | 10000 | 36000 | 18000 | 84% |
Sunnyvale’s survey showed that over 50% of respondents said that they would be more likely to cross the tracks by walking and bicycling if the intersection was separated from the tracks. So the outcome of closing Sunnyvale avenue to cars would likely to be to divert some of those 16% of trips to walking and bicycling, rather than shifting cars to the overpasses. Shifting to walking and bicycling would help the city achieve its sustainability goals.


The vehicle underpass would add more conflict points between vehicles, cyclists and pedestrians. This design would also make the crossing longer for pedestrians, who would need to walk 400 more feet to cross the tracks compared to existing conditions, and even longer for cyclists on Evelyn Ave who would need to travel an extra 1200 feet and traverse three more intersections to cross the tracks. And, an undercrossing with vehicles would bring more cares to Sunnyvale Avenue which is currently the city’s most-used North/South bicycle corridor.
Mary Avenue Undercrossing
The city council will also be discussing the Mary Ave undercrossing, with a staff recommendation for a Jughandle design. However, the staff report notes that safety features for pedestrians and cyclists will be considered at later phases of the project design.

Bike Sunnyvale, a local chapter of the Silicon Valley Bicycle Coalition, will be advocating for protected intersections and protected bike lanes to be included the Jughandle design. Recommendations from Bike Sunnyvale for pedestrian and cyclist safety include:
- Study building class IV fully-separated bike lanes on Mary: They should be at the same level as the sidewalk.
- Study adding protected intersections with intersection crossing markings: People on bicycles will find turning between Evelyn and Mary Avenues stressful because it will involve merging across traffic to get to the left hand turn lanes in up to 2 intersections. Adding protected intersections and crossing markings will make these maneuvers much more pleasant by removing nearly all driver/cyclist conflict points.
- Staircases connecting Mary Ave and Evelyn Ave so people walking can get to their destinations more quickly.
- Install crosswalks on each edge of the intersections: Mary Ave and Evelyn Ave to offer people walking and biking more options for crossing the street.
- Prohibit Right-Turn-on-Red: Permitting rights on red increases pedestrian crashes by 60 percent and bike crashes by 100 percent, according to the Insurance Institute for Highway Safety.
- Signaling Changes: When planning for vehicle traffic signal timing, consider adding dedicated bicycle signals and leading pedestrian and cyclist intervals to improve safety in these intersections. These additional signals and timing changes give people walking and biking a “head-start” before vehicle traffic is allowed to proceed and will reduce injuries and save lives.
- Minimize vehicular lane widths: This encourages drivers to drive slower and with greater attentiveness to other road users.
Do you live, work, or visit Sunnyvale? If so, please share your thoughts during the public comment at the Sunnyvale City Council Zoom meeting on Tuesday, Aug 30th at 7-9 pm, agenda item #3 .
And, if you agree with the Bike Sunnyvale recommendations you can sign the petition, here.
Content for this post contributed by Ari Feinsmith of Bike Sunnyvale.
It’s worth noting that VTA route 55 crosses the tracks at Sunnyvale Ave. This is a fairly busy route and care should be taken that the bus is not slowed down. A minor detour onto Mathilda and then California Ave might work, but we should take this opportunity to improve local transit too!