BART will halt train service between Union City and Warm Springs/South Fremont for five weekends between July and September so crews can replace a critical interlocking near Fremont Station. During those shutdowns, AC Transit will run free replacement buses that function both as a direct bus bridge between Union City and Warm Springs/South Fremont and as hopper shuttles that stop at Fremont Station. Riders in the area should expect trips to take longer, with BART warning of delays of roughly 30 to 40 minutes through the work zone.
When trains will be out
BART lists the five shutdown weekends as July 25-26, August 15-16, August 29-30, September 12-13 and September 26-27, describing the project as part of its ongoing system rebuilding work. Free buses from AC Transit will move riders between Union City, Fremont and Warm Springs/South Fremont, and BART cautions that the Green Line will be suspended on those weekends. According to BART, riders should plan for roughly 30 to 40-minute delays through the affected segment.
How the bus bridge will run
BART's post on X explains that the replacement buses will provide nonstop trips between Union City and Warm Springs/South Fremont, along with hopper buses that also stop at Fremont Station so customers can connect to trains north of the work zone. The agency says AC Transit will operate these buses free of charge during the shutdown weekends to keep riders moving while crews work in the trackway.
Free buses will replace trains between Union City and Warm Springs/South Fremont stations this weekend while BART crews are in the trackway to replace an interlocking, which is a critical portion of the system that allows trains to safely move from one route to another.… pic.twitter.com/1CgrnD7rK1
— BART (@SFBART) July 22, 2026
Fremont Station will be open for buses only
Fremont Station will stay open for bus service but will not offer train service on the shutdown weekends, according to the station advisory. Riders coming from the bus bridge who are heading to San Francisco should plan to transfer at Bay Fair to a Blue Line Daly City train, and BART notes that northbound departure times will be adjusted on work weekends to fit the temporary setup. For station details, see BART.
Plan ahead
Expect longer trip times, allow extra time for transfers and bus boarding, and leave early if you have a tight connection. Check schedules and the Trip Planner before you travel so you are not caught off guard during the shutdown weekends.
