Transportation

Petaluma section of Highway 101 widening project celebrated

Petaluma Highway 101 ceremony
Kenneth Kao photo

(L-R) Petaluma Vice-Mayor Dennis Pocekay, State Senator Mike McGuire, Congressman Jared Huffman, Sonoma County Transportation Authority Executive Director Suzanne Smith and Ghilotti Construction's Timothy Salles help celebrate the opening of new lanes on Highway 101 in Petaluma on Friday.

A celebration of the opening of the southbound carpool lane on Highway 101 in Petaluma was held Friday.

The lane is the final milestone on the Petaluma Widening Project that adds north and southbound carpool lanes between Corona Road and Lakeville Highway (State Route 116.) The project was led by Caltrans and the Sonoma County Transportation Authority.

The three-year, $122 million project includes $85 million in funding from Senate Bill (SB) 1, the Road Repair and Accountability Act of 2017, and $37 million in funding from Sonoma County’s Measure M. 

The Petaluma Widening Project included raising and widening the North Petaluma Overhead, building a bridge over the Sonoma-Marin Area Rail Transit tracks and a new bridge over Rainier Avenue, adding a new northbound auxiliary lane between Lakeville Highway and East Washington Street, and installing four new sound walls.

The project reached a milestone in November 2021, when the northbound carpool lane opened. With the opening of the southbound carpool lane, motorists will experience the full benefits of the project.  

"This final piece of Highway 101 improvements caps a two-decade effort to complete carpool lanes from Petaluma to Windsor," said Suzanne Smith, Executive Director of Sonoma County Transportation Authority. "Thanks to voters who approved local funds, as well as our partners in the Bay Area, the State, and Washington D.C., we now have reliable and improved infrastructure that will support the movement of people and goods."

The newly added lanes bring the total to 60 miles of carpool lanes between Petaluma and Windsor.

Completion of the Petaluma Widening Project brings to fruition a $1.2 billion Sonoma County plan for Highway 101 between Petaluma and Windsor to boost transit and carpool use, improve highway safety and traffic operations at interchanges, and support evacuations during emergencies.

The project is one of 13 projects on the Marin/Sonoma Narrows Widening Project, a regional endeavor to add 17 miles of carpool lanes in each direction on Highway 101 between State Route 37 in Marin County and Corona Road in Petaluma.

For more information visit the Petaluma Widening Project webpage