Road closures announced due to Highway 101/State Route 25 interchange construction

Starting later this month, commuters and other motorists navigating U.S. 101 through Gilroy will see permanent road closures due to construction on the freeway’s interchange with State Route 25, according to the Valley Transportation Authority. 

Starting April 16, access to U.S. 101 from Castro Valley Road and Mesa Road will permanently close. After April 16, traffic going to Gavilan College in Gilroy will use Monterey Road to West Luchessa Avenue, then Thomas Road to Santa Teresa Boulevard, VTA said in a press release. 

Traffic control and detour signs will be placed in the area for guidance. 

The road closures are part of a “major improvement project” that includes a new, extended southbound off-ramp from Highway 101 to State Route 25, VTA said. The improvements are designed to improve traffic flow and safety at the historically traffic-plagued highway interchange. 

Phase 1 of the Highway 101/State Route 25 interchange project will reconstruct the existing intersection, displacing it slightly north of its current location, according to VTA staff. Crews will replace the SR 25 two-lane overcrossing with a four-lane overcrossing spanning Highway 101. 

The project will also increase the length of the southbound US 101 off ramp to SR 25; upgrade the northbound US 101 ramps to improve exit and merging maneuvers; install new traffic signals at the ramp intersections to regulate traffic flow; and build a separated two-way bike lane between Castro Valley Road and the southbound 101/25 intersection. 

Future phases of the project will be announced and detailed as funding becomes available, VTA officials said. 

The total projected cost of the Phase 1 project is about $136 million, according to VTA. Of that amount, $77 million is funded by 2016 Measure B Santa Clara County sales tax and $59 million is from Senate Bill 1, known as the Road Repair and Accountability Act of 2017. 

Construction of Phase 1 is expected to begin soon and last through fall 2027. 

The project is designed to enable future improvements to both Highway 101 and SR 25, VTA added. Potential future upgrades include converting the intersection to a partial cloverleaf or diamond ramp configuration with direct connectors, frontage roads and grade separations between SR 25 and the Union Pacific Railroad crossing east of US 101.

For project updates, visit vta.org/sr25 or contact VTA Community Outreach at 408.321.7575.