Hwy. 101 underpass delayed again. Here’s when SLO County project will be complete
A year after construction started to improve one of San Luis Obispo County’s deadliest crossroads, crews are still months away from completing the $12.2 million project north of Paso Robles.
The California Department of Transportation is currently building a new underpass beneath Highway 101, where it intersects with Wellsona Road, near the San Paso Truck Stop between Paso Robles and San Miguel.
The safety improvement project was launched after several traffic fatalities occurred at the crossroads.
The intersection is the second-deadliest crossroad in San Luis Obispo County in terms of the number of traffic fatalities over the past decade, The Tribune previously reported.
Although roadwork was originally slated to wrap up in early 2026, Caltrans now anticipates the underpass will not be done until the spring, according to spokesperson Kevin Drabinski.
Here’s why the project has been delayed again.
What is the Wellsona Road Safety Improvement Project?
Caltrans is constructing a new 112-foot underpass beneath Highway 101, as well as frontage roads connecting the underpass with Wellsona Road on both sides of the highway.
The improvement project is intended “to reduce the number and severity of collisions” at the crossroads of Highway 101 and Wellsona Road, according to Caltrans.
Eight people died in vehicle crashes at the intersection between 2014 and 2024, The Tribune previously reported, which puts the fatal collision rate at the crossing higher than the state average, Caltrans said.
Once the new underpass is finished, drivers will no longer need to make left turns or drive across highway traffic, according to the state road agency.
“This would prevent future broadside and left-turn merge-related collisions at the intersection,” Caltrans said in its project report.
Long road to improving dangerous SLO County intersection
Caltrans first announced plans for the underpass in 2017, with the county advancing funding for the project in 2020.
At the time, construction was predicted to begin in winter 2022.
However, routine delays kept stalling the construction start date, Caltrans previously told The Tribune.
The biggest challenge was gaining land-use permits — also called right-of-way easements — from property owners in the area.
Finally after eight years of planning, Caltrans broke ground on the project on Jan. 14, 2025, with a projected completion date in early 2026.
Why was construction extended? What work still needs to be done?
Caltrans crews were delayed by several weeks after a series of atmospheric river storms swept through the county during the holiday season.
Due to the wet conditions, the project is now slated to wrap up in late April, Drabinski told The Tribune.
Crews still have a long list of remaining work that needs to be done, including completing the northbound bridge, building the San Paso Circle, installing electrical and lighting at the Wellsona Road and San Paso Circle intersection and constructing the northbound acceleration lane, according to Caltrans.
While work is underway, Highway 101 will continue to have two lanes of traffic flowing in both directions.
In the months ahead, however, there will be occasional lane closures to facilitate changing traffic patterns amid the project’s final stages, Drabinski said.
He urged drivers to “exercise caution and obey posted speed limits,” while traveling through the construction zone.
This story was originally published January 15, 2026 at 5:00 AM.
