Caltrans in Region 4 announced A new temporary roundabout will open at highways 116 and 121 at the Bonneau Road intersection, replacing the existing four-way stop, starting at 5 a.m. on Tuesday, Nov. 12.

After six months of construction, the new roundabout will help improve traffic flow and reduce congestion in the area. The project will be completed by the end of 2025.

In preparation for the new temporary roundabout, single-lane closures on the motorways will be in effect from 9pm until 5am on Monday night. Weather permitting, at least one lane in each direction will remain open while all work continues.

While this roundabout is temporary, it will follow the general flow of the final design, which will be completed next year but will lack some components of the completed roundabout, including sidewalks, bicycle and pedestrian lanes, an additional travel lane and a park. and driving characteristics.

Additionally, there is some good news for Sonoma Valley drivers; The temporary roundabout will reopen the bypass connecting northbound Route 121 to eastbound Route 121, further reducing congestion. However, this lane will temporarily close again in spring 2025 as Caltrans constructs sidewalks in the area.

If severe storms or power outages affect the area, the roundabout will not be affected as the construction allows for a steady flow of traffic without the use of electronic signs.

Construction of the new roundabout is a $26 million joint project with Caltrans and Sonoma County Transportation Authority (SCTA).

The project is part of Caltrans Complete the Streets ProgramAiming to provide California drivers with safe and efficient roads through community engagement.

To create the most accessible and safe solution for the original four-way stop at the intersection, Caltrans and SCTA evaluated two construction alternatives and selected the roundabout option over the signalized intersection to reduce traffic and promote safer driving.

“Caltrans encourages everyone to drive slowly and use caution as we all adjust to the new order,” Caltrans said in an Instagram post Sunday. “Roundabouts help keep speeds down and reduce serious collisions, making the junction safer for everyone in the long run!”

For more information and real-time updates Caltrans Quick Map or follow @CaltransD4 on Instagram or X (formerly Twitter).

Reach Staff Writer Isabel Beer at 707-933-2734 or [email protected]. on X (Twitter) @IsabelSongBeer