Highway 12 Paving in Santa Rosa

In early July 2023, Caltrans began a paving project on a three-mile stretch of State Route 12 (SR-12) between Llano Road and Farmers Market Road in Santa Rosa to replace worn-out pavement. 

This section of Highway 12 is composed of two types of pavement.  From Llano Road to Fulton Avenue the highway is composed of asphalt, while the section between Fulton and Farmers Lane is composed of concrete slabs.  As such, different construction and paving strategy will be used to revamp the pavement.  

During the project, Caltrans will also replace 11,000 feet of guardrail.  

Route 12 Santa Rosa Map

Pavement Condition -

Caltrans will smooth out the new concrete before completing the concrete slab replacement portion of this project. In other words, the new concrete is not in its final condition. Using a grinder, Caltrans work crews will grind the rough concrete into a smooth surface before finishing this project. 


Upcoming weekend closures listed below: 

Caltrans chose to implement full nighttime and partial daytime freeway closures to accelerate the demolition and replacement of concrete slab work that may take up to a year if performed during typical nighttime lane closures. Also, full nighttime closures are safer for workers and motorists. 



Caltrans will close State Route 37 in Solano, Napa and Sonoma counties on this weekend also. However, the Route 12 closures affect eastbound traffic while the Route 37 closures affect westbound traffic, so any conflicts will be minimal. Caltrans will provide updates if work is postponed or cancelled due to weather. During night closures motorists who wish to connect from eastbound Route 12 to US Hwy 101 will be detoured.  See maps below: 


Weekend Friday, April 19 - Monday, April 22, 2024 - Eastbound Route 12

Night and Day Closures GraphicBetween Friday, April 19, and Monday, April 22, 2024, Caltrans will close lanes on eastbound State Route 12 to between the Dutton Avenue exit and the S. "E" Street exit to demolish and replace existing concrete slabs. All ramps connecting Highway 101 to eastbound Route 12 will also be closed.  See detour maps below.  Westbound Route 12 will not be affected. 



FULL Nighttime Closures on Westbound Route 12

Friday, April 19 from 8:00 PM until 8:00 AM on Saturday, April 20.

Saturday, April 20, from 8:00 PM until 8:00 AM on Sunday, April 21.

Sunday, April 21, from 8:00 PM until 5:00 AM on Monday, April 22.



One Lane Closure on Westbound Route 12 (One of two lanes will be closed)

Saturday, April 20 from 8:00 AM until 8:00 PM 

  Sunday, April 21 from 8:00 AM until 8:00 PM


Click here to read the traffic advisory.

Day Detour   Overnight detour




Weather has always been a consideration for this project.  Paving is best done when the weather is warm.  If temperature dip into the 40s, there's a good chance the pavement won't bind properly, and the newly laid asphalt will need to be replaced.  The same hold true for the concrete sections. Warm weather helps the concrete to harden properly, which is essential to getting the road open on time. Naturally, the best season in which to pave or pour concrete is summer, when warm weather is the norm.  However, given the history of wildfire in Sonoma County and the importance of SR-12 as an emergency route, Caltrans decided to perform the bulk of the work during the cooler months.