The Bridges of Marin County

by Sandy Guldman
In recent newsletters we have mentioned changes to bridges, but in this issue, we are devoting an entire article to bridge projects, both large and small. There is no romantic interest in this tale (that we know of), but some changes are coming. We’ll start downstream and move upstream, describing what’s happening now and what’s coming up.

Replacing Bon Air bridge while keeping traffic flowing is a complex challenge. Photo courtesy of the City of Larkspur

Bon Air Bridge Replacement Anyone who lives in the lower Ross Valley or visits MarinHealth Medical Center (formerly Marin General Hospital) or doctors on South Eliseo has encountered the traffic disruptions and large cranes. The need for this project was driven by erosion of key components of the bridge. The new bridge will have a longer lifespan and improved access for pedestrians and bicycles. The large number of piles that support the old bridge and obstruct flow will be replaced with many fewer, more stable supports. To mitigate the impacts of the project, wetland habitat at Hal Brown Park and Piper Park will be created and enhanced. Improvements will also be made to a recreational dock in Greenbrae. The 4-year construction period allows the bridge to carry traffic most of the time, necessary because the bridge is a vital link to the hospital. At the present time, there are two temporary bridges used by workers. The City of Larkspur expects traffic to be switched to the new lanes on the north side of the existing bridge in January 2020, after which the temporary bridge on the north will be dismantled. Check bonairbridge.com for updates.

A shortcut path through the tidal marsh at Hal Brown Park is scheduled to be replaced by a low bridge in 2020. Photo by Sandy Guldman

Pedestrian Bridge in Hal Brown Park In contrast to the Bon Air Bridge, which is the most ambitious bridge project underway or planned for the near future in our watershed, the pedestrian bridge in Hal Brown Park is one of the smallest. It carries only foot, bicycle, and scooter traffic (some electric, so be alert). The bridge has reached the end of its useful life. Replacing it provides an opportunity to install a bridge and a connecting path that will not interfere with the flow of tides in the marsh and will be passable even at high tides. Marin County Parks expects to replace the bridge and path in summer 2020.
Bridge Avenue–Center Boulevard Complex These two bridges over San Anselmo Creek were built in the early 1940s. They are too narrow for the traffic and they also contribute to flooding. A combined project to replace both has been approved by Caltrans. Alternatives will be selected in the near future to deal with all three problems: capacity, flooding, and traffic flow.


Nokomis Avenue bridge contributes to local flooding, and is due to be replaced. Photo by Charles Kennard

Madrone Avenue Bridge and Nokomis Avenue Bridge These bridges over San Anselmo Creek were built in 1930. The existing sidewalks are narrow and do not comply with Americans with Disabilities Act requirements. Both roadways connect neighborhood residents to Sir Francis Drake Boulevard and Center Boulevard, primary thoroughfares leading into downtown San Anselmo and the greater North Bay area. The bridges are too narrow and contribute to flooding in the area, making them priorities for removal as part of the Ross Valley Flood Control Program. Selection of the preferred alternatives and final construction schedules will be announced in 2020.
Fairfax Bridges The Town of Fairfax is engaged in a multiyear project to rehabilitate five bridges that span San Anselmo and Fairfax creeks on Marin Road, Spruce Road, Canyon Road, Creek Road, and Meadow Way. Like many of the bridges in Fairfax, these were constructed eighty to ninety years ago. These bridges are showing the accumulated wear of decades and require preventive maintenance to insure they are safe for continued use.