Another overnight detour awaits as Highway 99/120 junction in Manteca is expanded
Drivers can expect a nighttime detour once again for the Highway 99/120 interchange upgrade in Manteca.
It will begin at 8 p.m. Wednesday, May 27, on the ramp from eastbound 120 to southbound 99. The ramp will reopen at 4 a.m. Thursday. The detour will be repeated at the same hours from Thursday night into Friday morning. It will be about a mile north on 99 to the Yosemite Avenue interchange.
The $48.2 million project will add a second lane to this ramp and a fourth lane on southbound 99 to Austin Road. It also includes a new bridge for Austin and connections to major roads in south Manteca.
The junction serves commuters to Bay Area jobs, some of them from Stanislaus County. The upgrade could be complete in summer.
Construction launched in August 2024 by Teichert Inc. of Pleasanton. It has needed detours from time to time.
The project is funded in part by San Joaquin County’s Measure K sales tax and fees on property developers. It also has money from state and federal transportation programs and federal payments to local governments amid COVID-19.
The public can get updates on the detours and other details from the San Joaquin Council of Governments, www.sjcog.org.
The agency still seeks about $90 million to improve other parts of the junction in two other phases by 2042. They would add lanes to both highways and to the ramps between them.
