Saving Highway 37 from flooding will be an expensive, long-term project
Studies predict the vital commute corridor will be under water in 40 to 100 years
The issues driving Highway 37 congestion work the same for Highway 12 through the Valley of the Moon – rising housing costs in Sonoma and Marin are driving more of their workforce to Solano and other East Bay counties in search of affordable housing.
The transportation departments of all four counties are working to find the best solutions to replacing or rebuilding the 21-mile corridor, which isn’t easy in the current fiscal landscape.
“There is no money for transportation projects,” Sonoma County Transportation Authority Director Suzanne Smith told the county supervisors on Aug. 9. “There are no Measure M bond funds, no North Bay tax measures, and very little likelihood of state action this year.”
In May of this year, United Bridge Partners, a private group, offered to rebuild the two-lane segment and finance it with tolls. California has very few privately funded roads, toll or otherwise, and special legislation would be necessary to make this work. That proposal will be considered, Smith said, along with every other type of possible funding.
Another funding issue is that Highway 37 is not the top priority for any of the four counties. Sonoma is focused on completing the Narrows project to widen 101 between Petaluma and Novato. Marin is working on the Interstate 580 approach to the Richmond Bridge. Solano is keyed to a similar approach to Highway 80. Napa’s top priority is Highway 29, the main north/south route through the county.
Statewide, the drop in revenues from the complicated gas excise tax formula is linked to a $5.7 billion drop in maintenance funds for state highways and a $7.8 billion loss to local road repair funding.
Possible alternatives“This is a transportation project, but it is also an environmental enhancement project,” Smith said, noting that Highway 37 passes through some of the most environmentally sensitive land in the Bay Area, “The value to the Bay is significant if we elevate and improve the tidal flows.” An environmental project might qualify for federal and private funding not available for purely transportation undertakings.
The Highway 37 corridor is four lanes at the east and west ends, connected with a two-lane segment in the middle that is the source of the worst congestion, running from Sears Point to Mare Island. Long range predictions by U.C. Davis studies show entire segments of the middle and western portions being completely inundated by rising sea levels in the next 40 to 100 years.
Just a few years ago, the preliminary judgment was to abandon the highway, First District Supervisor Susan Gorin said. “Since then, it has become a very critical linkage of the Bay Area transportation system.” Smith noted that Caltrans considers Highway 37 a primary route to be used in case of a major earthquake or other disaster.
Highway 37 is already deteriorating due to water levels that were eight inches higher in 2014-2015 than predicted by the U.C. Davis studies just a few years ago. The central segment is basically an elevated berm, or dirt mound, roughly 10 feet higher than the bay water level. In storm and high tide conditions, water can be at the nine-foot level.
The alternatives being considered include raising the berm, or building one of two types of elevated causeway. While reinforcing the berm is the cheapest method, the causeways offer many benefits to the environment, allowing water to flow unimpeded and improving the health of the North Bay marshes. They can be expensive, however, with a final price tag that could exceed $4 billion.
Doing nothing is not a viable alternative, Smith said. “If 37 was not available, traffic on Highway 116 would increase over 40 percent, and traffic over the Richmond Bridge (580) could rise over 60 percent. Neither one of those roads could handle that.”
A 2014 traffic study showed 32 percent morning traffic originating in Solano County and heading west, reversing in the evening.
More information about Highway 37 is available at the Sonoma County Transportation Authority website (Highway 37 planning) scta.ca.gov/projects/highway37/.