A car takes a turn along Castro Valley Road in Gilroy, Calif. Castro Valley Road is one of two roads that will be permanently closed beginning April 16 to make way for improvements to the busy interchange of U.S. Highway 101 and State Route 25. (Google)

STARTING NEXT WEEK, two roads that access U.S. Highway 101 south of Gilroy will be permanently closed to make way for improvements to the freeway’s busy interchange at State Route 25.

Castro Valley and Mesa roads will be closed as of April 16, according to the Santa Clara Valley Transportation Authority.

The closures are part of a project that includes a new, extended southbound off-ramp from U.S. 101 to State Route 25, also known as Hollister Road.

The project is aimed to improve traffic flow and safety. The existing interchange, just south of Gilroy in Santa Clara County, is over 30 years old and can no longer handle traffic demands, according to VTA.

An increase in traffic and travel speeds have led to higher-than-average accident rates in the area, and also caused traffic backups onto southbound Highway 101.

Valley Transportation Authority (VTA) graphic showing work to be done during Phase 1 of the US 101/SR 25 Interchange project south of Gilroy in Santa Clara County, Calif. The interchange currently cannot accommodate traffic demands due to the rapid growth in commuter, commercial, and recreational traffic that passes through this area. These conditions and high travel speeds have resulted in higher-than-average accident rates in the interchange area and traffic backups onto southbound US 101. (VTA via Bay City News)

After April 16, traffic going to Gavilan College can use Monterey Road to West Luchessa Avenue, then Thomas Road to Santa Teresa Boulevard.

Traffic control and detour signs will be in place. Updates on the project are available at vta.org/sr25. Information is also available at VTA Community Outreach at (408) 321-7575.