MTC funding helps North Bay Narrows project reach milestone

Marin-Sonoma Narrows
Marin Sonoma Narrows
Mark Prado

A 30-mile stretch of carpool lane has been connected on northbound Highway 101 in the North Bay from the Marin border to Windsor, which will improve traffic along a notoriously slow stretch of freeway known as the Marin Sonoma Narrows.

MTC has long identified improvements to the U.S. 101 corridor in the North Bay as an important regional priority, including the Marin Sonoma Narrows, where lanes narrowed from three to two creating bottlenecks.

MTC has contributed $15 Million in re-purposed federal earmarks, another $15.4 Million in STP funds and $23 Million in RTIP funds, and monies from the Prop 1B Corridor Improvement program, among other dollars. It also is advancing $76 in federal dollars toward the project. Caltrans, the Transportation Authority of Marin and Sonoma County Transportation Authority are partners on the project.

The latest milestone was reached Dec. 2, when Caltrans completed the northbound widening on the Washington Creek Bridge between Lakeville Highway (State Route 116) and the Lynch Creek Trail bridge just north of the E. Washington Street interchange. 

The newly widened Washington Creek Bridge was the last piece needed to complete an uninterrupted three-lane freeway on northbound Highway 101 between the Marin County Line and Windsor. 

The Petaluma widening project is one of 13 projects of the larger Marin Sonoma Narrows widening project to add a carpool lane in each direction of Highway 101 between State Route 37 in Marin County and Corona Road in northern Petaluma.

Only two roadway projects remain on the Marin Sonoma Narrows, including the Petaluma widening project, which is underway. The final project will begin in spring 2022, which will add carpool lanes between Novato and the Marin/Sonoma county border. 


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