A BART train at the San Francisco International Airport station - San Francisco

BART Runs One Track to SFO July 31 Through August 2 for Train Control Work

By Brian (Local SF Guide) · July 25, 2026

If you are flying out of SFO the weekend of August 1, add time to your BART trip. From 9pm on Friday, July 31 through the end of service at midnight on Sunday, August 2, BART is running trains on a single track between Millbrae, San Francisco International Airport, and San Bruno stations, the agency announced.

What to expect

BART says riders should plan for delays of 10 to 15 minutes for most of the weekend, rising to as much as 30 minutes in the work area on Saturday night. Platform assignments change at both Millbrae and SFO for the duration. At Millbrae, passengers transferring to Caltrain may have to walk farther than usual to reach the platform. BART is posting extra staff and temporary wayfinding signs at both stations.

Why the tracks are closing

Crews are installing about nine miles of cable for BART’s new Communications-Based Train Control system, or CBTC. The 55-hour window is what the work team needs to finish that segment safely, which is why the closure runs through a full weekend instead of a few overnight shifts.

CBTC is the reason BART has been doing repeated late-night and weekend work on the Peninsula since late 2025. Once the system is running, BART says it can operate trains closer together and raise transbay capacity from 24 trains per hour in each direction to 30.

Planning around it

Trains still serve SFO throughout the weekend. The change is frequency and reliability, not access. For an early flight, the practical advice is to catch a train one departure earlier than you normally would and check real-time departures before you leave. Travelers headed to Millbrae for Caltrain should budget a few extra minutes for the longer transfer walk.

The single-tracking ends before BART’s systemwide schedule change takes effect on August 10, which brings longer trains and rewritten timetables across the network. We covered what changes in our guide to the August 10 BART schedule.

Photo: Pi.1415926535, CC BY-SA 3.0, via Wikimedia Commons.