Motorists on Highway 101 in southern Sonoma County have noticed big changes taking place in recent months around the county line as the long-running freeway widening project takes shape through the Sonoma-Marin Narrows.
Unfortunately, traffic relief is not expected for at least another year as the complex project drags on. Separately, funding for other key bottlenecks not yet under construction is in jeopardy because of a ballot measure and a court case.
Still, Sonoma County transportation officials remain hopeful that the entire stretch of Highway 101 from Windsor to Novato will be widened to six lanes by 2023, ending a $1.2 billion, two-decade effort to remake the region’s most important transportation corridor.
“It will feel great when the Narrows are finally widened,” said Supervisor David Rabbitt, a board member of the Sonoma County Transportation Authority. “We have a funding plan in place, which is wonderful. We have a path forward.”
A new bridge at the county line over San Antonio Creek is nearly complete, according to James Cameron, director of projects and programming at the transportation authority. Southbound drivers are already using the new bridge, which is wider, straighter and higher above the creek than the flood-prone twin spans being replaced.
In November, northbound traffic is expected to shift onto the new bridge, marking a key moment in the construction project. The move will mean that, for the first time since the highway was built in the 1950s, adjoining properties will no longer have direct access to Highway 101.
Several driveways still feed into the northbound lanes near the county line, and it is not uncommon to see mail trucks idling on the shoulder, delivering to mailboxes that front the highway. This is just one of the dangers transportation officials hoped to remedy with the widening project.
After the upcoming traffic shift, the old northbound lanes will become a new frontage road, an extension of Petaluma Boulevard South, that will serve the properties in the Narrows, Cameron said. This road, and a parallel road on the west side of the freeway, will dead-end at the county line. Officials intentionally designed these frontage roads to serve local traffic and not provide an alternative to Highway 101.
A new bike path along the frontage road slated to open next year will connect to San Antonio Road and a bike path along Olompali State Park, making it possible to cycle through the Narrows from Petaluma to Novato, a long-sought goal of local cyclists.
Once the shift onto the new San Antonio Creek bridge is complete, there will still only be four total lanes of traffic in the area, Cameron said. Complete striping of the carpool lanes from the Petaluma River to the county line is contingent on a separate widening project just to the north at Kastania Road, which started later.
“We’re on schedule to open the carpool lanes at the end of 2019,” said Suzanne Smith, executive director of the transportation authority. “It’s particularly going to be helpful for northbound commuters in the evening, who can get off at Petaluma Boulevard South or Highway 116 before the lane drop happens.”
That drop, from a total of six lanes to four, is just north of the Petaluma River bridge, the beginning of the final segment of the Highway 101 widening project in Sonoma County that, until May, was unfunded. This past spring, state officials awarded Sonoma County $85 million to widen Highway 101 through Petaluma from the river to Corona Road.