Highway 101 widening in Petaluma moves to demolition phase

The Highway 101 widening project in Petaluma is entering another phase that recently elevated southbound drivers who spent months traveling in lanes several feet below motorists heading in the opposite direction.

Beginning Monday, construction crews will begin demolishing the southbound lanes between East Washington Street and Corona Road. Because of this, southbound travelers were shifted into temporary lanes in the center median about a week ago.

Demolition is scheduled to take place on weekdays through October, but it’s unlikely to impact traffic.

“By and large, people in the new southbound configuration, they wont be able to see us working on the existing bridge,“ said Brian Beaudoin, a Caltrans civil engineer.

Crews are removing a stretch of road that passes over Sonoma-Marin Rail Transit tracks, but is still at a lower elevation than the northbound lanes built earlier this year.

Though most work will happen on weekdays, Caltrans has scheduled 33 hours of consecutive work from 8:30 p.m. Saturday to 5:30 a.m. Oct. 18 when no SMART trains are expected.

Southbound traffic will be using the center median until summer and conditions should be similar to what drivers in the opposite direction experienced months ago when the old northbound lanes were removed.

The shift caught some motorists by surprise.

“I last drove this way in July. Today, I’m passing through and it was different,” Novato resident Henry Glass, 69, said Wednesday after stopping for gas in Petaluma. “I was higher up than I remember.”

Carpool lanes are being added to both directions of Highway 101. Once the southbound bridge is removed, crews will begin building a new three-lane bridge.

The entire width of the freeway will increase from about 48 feet to 120 feet and Beaudoin said “We’re going to have shoulders and full lanes in the new configuration.”

It’s only a portion of the much-larger effort to expand Highway 101 from two lanes to three lanes along a 16-miles stretch of Highway 101 from state Route 37 in Marin County to Corona Road in Petaluma.

The Marin-Sonoma Narrows Project has been ongoing for 20 years and the current work is part of its final phase. The entire project is expected to cost at least $754 million and the existing phase should wrap up by late 2022.

Once the Petaluma portion is done, all that’s left is a 6-mile Marin County segment from Atherton Avenue in Novato to San Antonio Road, south of the Marin-Sonoma County line.

That widening work begins this spring and should be finished in late 2023 or early 2024.

You can reach Staff Writer Colin Atagi at colin.atagi@pressdemocrat.com. On Twitter @colin_atagi.