Welcome to Caltrans District 4

U.S. 101 - North B project Airport Blvd Interchange and Windsor Sound Walls

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On Wednesday morning, May 7, Caltrans will switch traffic to the new Airport Boulevard bridge. A new traffic signal at southbound off-ramp from U.S. 101 will allow traffic to travel east or west on Airport Boulevard. A second traffic signal will allow access for eastbound and westbound traffic to the new northbound U.S. 101 on-ramp. The northbound loop on-ramp will be permanently closed.

On Saturday night, May 10, Caltrans will begin demolition of the old Airport Boulevard bridge. Demolition is a noisy activity, and residents may hear more noise during nights of bridge demolition. Please see the traffic advisory for more information about this work.

This project is part of the Proposition 1B Corridor Mobility Improvement Account (CMIA) Program. This project will convert the two existing partial interchanges on U.S. 101 at Fulton Road and at Airport Boulevard into a single complete interchange at Airport Boulevard, eliminating the on- and off- ramps at Fulton Road. The project will also replace the existing two-lane Airport Boulevard Overcrossing at U.S. 101 with a new five-lane overcrossing bridge structure (four through lanes and one turning lane), sidewalk, and Class II bike lanes, in addition to constructing sound walls in Windsor.

The U.S. 101 corridor connects San Francisco and the East Bay with Marin, Sonoma, and Mendocino Counties. The corridor is increasingly congested and improving the operational efficiency at this interchange is vital to the continued growth of Sonoma County and the region beyond.


The projectís improvements will reduce travel delay, decrease congestion, improve operational clarity and efficiency, and improve traffic flow on local streets at the Airport Boulevard Interchange and on U.S. 101.


The project is developed through a partnership among the Sonoma County Transportation Authority (SCTA), the Metropolitan Transportation Commission (MTC), Sonoma County, and the California Department of Transportation (Caltrans).

Project Status

The environmental phase was completed in October 2010, and the design phase was completed in April 2012. Construction bids were opened on October 17, 2012 with the project awarded on December 3, 2012 to Ghilotti Construction. The project is currently in construction.

Project Costs and Funding

Projectís construction capital cost is $28.7 million.

Project Schedule

Start Construction: Spring 2013
Finish Construction: End of 2014