Caltrans is seeking redesign ideas for SR37, ahead of predicted climate change-related road flooding

If you’ve driven State Route 37, you probably know how often the Bay Area commuter route experiences a major traffic slowdown. Now the state of California plans to revamp the Highway 37 corridor through projects expected to cost more than a quarter of a billion dollars.

37 is North Bay most trafficked the highway in an east/west direction, causing not only long and significant delays, but also occasional flooding during winter storms. People use the 21-mile route to get to work, but tourists from San Francisco also use it to travel to wine country in Napa and Sonoma counties. Four Transportation In December 2015, traffic authorities in three North Bay counties (Sonoma, Napa and Solano) signed a Memorandum of Understanding aimed at solving the problems the highway will soon face, and there are now new plans for moving forward.

Like Caltrans explains, the reconstruction is in its early planning stages and construction work will not begin for several years or more. However, the state believes it is crucial to rebuild or reroute the road to avoid a projected sea level rise that would cause major flooding by 2040 and completely sink the street by 2050.

Photo: California Department of Transportation • Caltrans

Because the route passes through protected and important marshes, environmental studies in improvement projects must take into account the needs of the sensitive ecosystem as well as the objective of finding solutions to future traffic patterns and flooding.

There has already been work to try to protect the road, which crosses San Pablo Bay, one of the largest remaining tidal marshes in the Bay Area. For the past 30+ years, federal and state government agencies have partnered with nonprofit environmental conservation organizations to restore habitat.

“Caltrans reviewed over 120 miles of preliminary alignments for evaluation in the planning and crossover study”, says the agency.

The Sears Point Improvement Project at Mare Island offers some options for the 10.4-mile stretch of SR 37 that runs between Sonoma and Solano counties. In this stretch, the highway narrows to one lane in each direction, creating a bottleneck. The improvement project has several alternatives for the cross sections. The first is to incorporate a reversible lane, so peak periods could have two lanes going one way and one the other to account for extra traffic directed in one direction only. It could cost approximately $256 million up front, plus $2 million annually for maintenance and staffing.

The second alternative proposes to incorporate a new track but also to add a fixed median. The additional lane would be chosen for the eastbound or westbound lane depending on peak travel times and would cost around $306 million.

Other proposals are to either have two lanes in each direction with reduced shoulder width, or four lanes in total with regular shoulder width. These would round up a bill between $325 million and $415 million.

Other ideas move away from simply adding new lanes. Some believe the best option is to raise the highway or build a new levee system. There are also concept designs to redirect the highway further north.

Some offer a bridge over San Pablo Bay with a separate bike path and walkway. With this notion, the state would like to add public transport options like bus routes or workarounds for ferries and trains.

Top Image: Sonoma County Transportation Authority

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