MARIN COUNTY – Drivers in Marin County will soon have access to a new stretch of high-occupancy vehicle lanes in northern Novato, an opening that will create a continuous span of “carpool lanes” down to the Richardson Bay Bridge.

Expected for completion in August, the lanes will mark the latest step in alleviating the slowdown that typically occurrs in the two-lane bottleneck between Marin and Sonoma counties known as the Marin-Sonoma Narrows.

In all, approximately $225 million has been invested in improving Highway 101 in Marin County since work began to close gaps in the region’s HOV lanes in 2001. The latest round, a $29.7 million grant from the California Transportation Commission, will go toward new frontage roads and creating a new interchange in the area of the Redwood Landfill.

Yet while approximately $80 million more is needed to fully extend HOV lanes to the border with Sonoma County, Transportation Authority of Marin Executive Director Diane Steinhauser said that drivers have already experienced marked improvements in commute times since work began, noting that officials chose to focus funding on safety-oriented projects before pursuing further widening.


Sonoma County will need approximately $177 million to add an HOV lane on its side of the Narrows, but Ms. Steinhauser said that she was confident that state and federal entities would support enhancements to the main artery linking travelers and commerce from San Francisco to the Redwood Empire.

One source of potential funding could include the commission’s Corridor Mobility Improvement Account, composed of Proposition 1B funds that were saved when contractors bid lower than expected.

The commission awarded $82 million to Sonoma County last month to help fund construction of a new bridge and frontage roads in Petaluma, as well as $24.1 million in April to fund the construction of a new interchange at Airport Boulevard.

Work on the new interchange and frontage roads in the Narrows area is expected to be completed in 2015, said Robert Haus, a spokesman for Caltrans.

“That’s part of upgrading from highway to freeway status,” he said.