Expect 30-minute delays starting at 9pm some Sunday-Thursday nights between Millbrae and SFO, plus delays in the area for train control modernization work through Summer 2026

The trackside construction work to replace BART’s aged train control system with a modern Communications-Based Train Control (CBTC) system has reached a new phase that will cause evening service delays between Millbrae, SFO, San Bruno and South San Francisco stations. Expect 30-minute delays starting at 9pm on some Sundays-Thursdays for riders travelling between Millbrae, SFO, and San Bruno stations due to planned train control modernization construction work.

BART staff will update the Trip Planner on a weekly basis to indicate if the work is taking place each week. 

This construction and the service impacts in this area are expected to continue until Summer 2026. 

The work was first announced in January 2025 with changes to service for Millbrae riders after 9pm with a shuttle train running every 15 minutes between Millbrae and SFO, making loops, with an easy cross platform transfer at SFO to board a Yellow Line train if continuing on. However after midnight, the final Yellow Line trains to SFO station proceed to Millbrae (riders will not need to transfer for Millbrae service), and the final train of the evening bypasses SFO, as it always does, and goes straight to Millbrae.  

The shuttle train service plan for Millbrae riders is expected to last through 2026 as BART has prioritized this section of track to be the first area to bring on CBTC in the BART system.  

The next location to begin construction will be between Colma and Glen Park in early 2026. 

The state-of-the-art CBTC system will transform BART service by enabling trains to run closer together. A modernized train control system will enable BART to increase projected Transbay capacity to 30 trains per hour per direction in the core system area, up from the current limitation of 24-trains per hour per direction.