State Route 37 Sears Point to Mare Island Improvement Project

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Other Agencies with Actions or Authorizations: Department of the Interior, Fish and Wildlife Service Department of Commerce, National Oceanic and Atmospheric Administration Department of the Army, US Army Corps of Engineers - Regulatory Description: The California Department of Transportation (Caltrans)—in cooperation with the Metropolitan Transportation Commission (MTC) and the north bay partner agencies of Sonoma County Transportation Authority (SCTA), Solano Transportation Authority (STA), and Napa Valley Transportation Authority (NVTA)—is proposing improvements to the portion of State Route (SR) 37 that is one lane in each direction. Caltrans is the lead agency under CEQA and NEPA. The section of SR 37 proposed for widening is a two-lane conventional highway between SR 121 and the Mare Island Interchange (approximately 9 miles). East of the Mare Island, Interchange SR 37 is a four-lane freeway facility between Interstate 80 (I-80) and Mare Island (approximately 4.5 miles). West of SR 121, it is a four-lane conventional highway between SR 121 and United States Highway 101 (U.S. 101) (approximately 7.3 miles). The highway allows local road and driveway access from adjoining properties, has acceleration and deceleration lanes at some local intersections, and has an existing median barrier along most of the route. Bridge crossings are at Sonoma and Tolay creeks. The project is within or adjoins the counties of Sonoma, Solano, and Napa and would add a high-occupancy vehicle (HOV) lane(s) from just west of SR 121 to the Mare Island (Walnut Avenue) Overcrossing, within the portion of SR 37 that is currently served by only one lane in each direction. Four alternatives are being considered. Each of the four Build Alternatives would reconfigure the existing SR 37 highway lanes from west of the SR 121 intersection to the Walnut Avenue Overcrossing at Mare Island. Each alternative would involve widening the existing bridge over Tolay Creek.

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