Sonoma County Quarterly Caltrans Update

Welcome back to the Caltrans Sonoma County Newsletter, your guide to Caltrans activities in the county. This is our second Sonoma County newsletter, and we hope you like it!

In this newsletter, we’re sharing news about projects past, present, and future as well as other Caltrans activities that will be of interest to motorists, transit users, cyclists, and pedestrians who use the state highway in Sonoma County.

If you live, work, represent or serve Sonoma County, this newsletter is for you. If you look to the left, you’ll see a list of resources to get things done, like reporting potholes, litter and graffiti.

Feel free to give us feedback. If there are specific projects you’d like to see covered, let us know.

Some current activities: Caltrans will be closing Route 116 in Forestville from June 28-July 1, and work is continuing on the Route 116/121 Roundabout Project southeast of Sonoma. Also, we’ll be upgrading sidewalks on Route 116 in Guerneville in late summer.

Read on for details.


Visit our project website for additional updates.

For project questions & to sign up for our weekly newsletter, please contact us at EMAIL.

Three-Day Closure of Route 116 in Forestville to Strengthen the Jones Creek Bridge

As part of an emergency project to strengthen the Jones Creek Bridge on State Route 116 in Forestville, Caltrans will close the highway between Packing House Lane and Kay Lane for 72 hours from 7:00 PM Friday, June 28, until 7:00 PM Monday, July 1, 2024.

Two lanes of traffic crosses Jones Creek Bridge on State Route 116 in Sonoma County.

During a recent bridge inspection, Caltrans found the 22-foot, two-lane Jones Creek Bridge overloaded with asphalt from years of paving. The excess asphalt needs to be shorn to reduce weight.

Map showing the location of the Jones Creek Bridge on State Route 116 near Forestville in Sonoma County.

Per regulation, the bridge must be strengthened before the end of July; otherwise, Caltrans must operate one-way traffic control over the bridge until the issue is rectified.

Map showing the detour route during the closure of the Jones Creek Bridge on State Route 116. During the closure, Caltrans will detour traffic onto Mirabel Road, River Road, Laguna Road, and Guerneville Road.

During the closure, Caltrans will detour traffic onto Mirabel Road, River Road, Laguna Road, and Guerneville Road. (See detour map.) 

The Jones Creek Bridge has one lane in each direction, and much of the strengthening work must be performed in the middle of the bridge, factors that make it nearly impossible to do the work without fully closing the bridge. 

In addition to removing excess asphalt, Caltrans plans to strengthen the bridge by installing precast concrete girders that will rest on the bridge's abutments, not the roadway itself. These girders will be topped with concrete panels, creating a lighter yet stronger roadway. Finally, the asphalt layer will be added over the panels to produce a smooth driving surface. 

Motorists should allot extra time if planning to travel through this area during the closure weekend. 

Changing Traffic Alignments of Hearn Avenue Overpass Project

Building a new Hearn Avenue Overcrossing while accommodating traffic on the existing overcrossing is no mean feat, and entails modifying traffic routes to allow construction work to happen. Caltrans has closed two turn pockets on the northwest side of the project to create space to build the first phase of the new overcrossing.

The temporary traffic impacts will be worthwhile as the new structure will add two new traffic lanes, east and west sidewalks, and a pair of traffic-separated bicycle lanes. 

Work Continues on Route 116/121 Roundabout

An overhead rendering of the new roundabout that recently began construction at the intersection of State Route 116 and State Route 121 in Sonoma County.Caltrans continues working on the Route 116/121 Roundabout Project southeast of Sonoma. Construction work is expected to expand into a new area in the next few months, so motorists should watch for changing road alignments.

Sidewalk Upgrade Project on Route 116 in Guerneville Begins Late Summer

Project includes landscaping courtesy of Caltrans/Sonoma County Partnership

Caltrans will begin a project in the late summer of 2024 to upgrade sidewalks, replace traffic signals, and add pedestrian beacons on State Route 116 in Guerneville between River Road and 4th Street.

The improvements include replacing 23 curb ramps with ramps compliant with the Americans with Disabilities Act of 1990 (ADA).

Cars are parked in front of shops on State Route 116 in Guerneville.Traffic signals at River Road and Highway 116 will be replaced. The sidewalk between River Road and Armstrong Woods Road will be widened at each light pole to provide a 48-inch clearance. Driveways will be reconstructed to conform with the new sidewalks.

To enhance pedestrian safety, Caltrans will install pedestrian hybrid beacons and curb extensions at the intersections of SR-116 at Church and Mill streets. The new pedestrian signals will be High-Intensity Activated Cross-Walk beacons (HAWK), which will alert motorists to the presence of pedestrians.

Also, curb extensions will be installed at several locations to slow traffic and reduce the distance pedestrians must travel to cross the street.

Caltrans and Sonoma County worked together to make other functional and visual improvements to the area, including adding 14 bike racks, 64 sidewalk sleeves for flags, and nine new tree wells.

Bar graph showing percent completed for three Caltrans projects in Sonoma County. Route 12 Paving is at 60%, SR116/121 Roundabout is at 5%, and Hearn Ave Interchange is at 5%.

The Sonoma County newsletter will be distributed on a quarterly schedule.

Caltrans bay area logoFor 24/7 traffic updates, please visit or
For real-time information, please visit Caltrans QuickMap:


Sonoma County Public Information Officer
Jeff Weiss

General Information
(510) 286-4444

Follow us for more! | Instagram | Twitter | Facebook | YouTube |