After nearly a decade, a major construction project to build an underpass at a deadly Highway 101 crossing in San Luis Obispo County is now complete.
The Wellsona Road Safety Improvement Project — a $12.2 million endeavor between Paso Robles and San Miguel — was officially finished Wednesday, the California Department of Transportation announced in a news release.
Caltrans built a new 112-foot underpass beneath Highway 101, along with frontage roads connecting the underpass with Wellsona Road on both sides of the highway.
The new undercrossing, which lies south of the existing intersection, “eliminates the need for motorists to make left turns across traffic” on Highway 101, Caltrans said in the release.
Caltrans built a new underpass beneath Highway 101, where it intersects with Wellsona Road, near the San Paso Truck Stop between Paso Robles and San Miguel. Caltrans District 5
Located near the San Paso Truck Stop between, the improvement project was originally launched “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.
The intersection was the second-deadliest crossroads in SLO County in terms of the number of traffic fatalities over the past decade, The Tribune reported.
The Cholame Y at the intersection of Highways 41 and 46 was the deadliest crossing. In June 2025, it was replaced by a flyover interchange, meaning both of the county’s two deadliest crossings have now been improved and reopened in less than a year.
A view of the intersection of Wellsona Road and Highway 101 shows a truck turning left onto Highway 101. The crossing has been the location of multiple deadly crashes and is slated for improvements with construction beginning in 2025. David Middlecamp dmiddlecamp@thetribunenews.com
Hwy. 101 underpass project complete after nearly a decade
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, but routine delays kept stalling the construction start date due to challenges obtaining right-of-way easements from property owners in the area, Caltrans previously told The Tribune.
After eight years of planning, Caltrans broke ground on the project on Jan. 14, 2025.
The underpass was projected to be complete earlier this year, but a string of atmospheric river storms drenched the site, delaying construction again.
But as of Wednesday, the underpass and frontage roads were finished and open to the public, Caltrans spokesperson Kevin Drabinksi told The Tribune.
“We’re excited that we brought this project to completion, which results in safer conditions to the traveling public,” he said.
Caltrans built 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. Caltrans District 5
See photos of work at Wellsona Road underpass
The Wellsona project took more than a year to complete.
See photos of the work over the last 15 months.
Caltrans will implement overnight lane closures on Highway 101 on April 7-9, 2026, in order to remove temporary barriers and install permanent delineation at the site of the new underpass and frontage road construction at the intersection of the highway and Wellsona Road. Courtesy of Caltrans
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. Caltrans District 5
Caltrans said the Wellsona Road Safety Improvement project is running slightly behind schedule, with construction expected to wrap up in late April after heavy winter rains caused delays. Caltrans District 5
Caltrans is 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. Caltrans District 5
Caltrans is building an undercrossing and frontage road near the intersection of Highway 101 and Wellsona Road north of Paso Robles. Seen here, crews work on the new southbound bridge for part of the Wellsona Road Safety Improvement Project. Caltrans District 5
California Department of Transportation crews are using an innovative, see-through tool called ClearCast to build a concrete bridge near the intersection of Highway 101 and Wellsona Road north of Paso Robles. Courtesy of Caltrans District 5
As part of a pilot project, the California Department of Transportation said using a transparent deck form, known as ClearCast, to create a bridge at the intersection of Highway 101 and Wellsona Road north of Paso Robles Courtesy of Caltrans District 5
The intersection of Wellsona Road and Highway 101 has been the site of several deadly collisions in recent years. A new truck-repair facility could be coming to the intersection before a planned underpass is installed, prompting safety concerns. Joe Johnston jjohnston@thetribunenews.com
Hannah Poukish covers San Luis Obispo County as The Tribune’s government reporter. She previously reported and produced stories for The Sacramento Bee, CNN, Spectrum News and The Mercury News in San Jose. She graduated from Stanford University with a master’s degree in journalism.
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