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How long will it take San Francisco to stop using floppy disks to run its trains?

Answer: Until 2030.

A black floppy disk laying on a white surface. The disk is partially covered by it's instruction manual.
The mantra “if it ain’t broke, don’t fix it” only works for so long. Eventually, even if a system is still working fine, you’re going to want to upgrade it. That’s the lesson from the San Francisco Municipal Transportation Agency (SFMTA), which still uses floppy disks to run the city’s Muni Metro light rail.

Each morning, the SFMTA uses three floppy disks to load the software that runs the central servers which operate the Automatic Train Control System (ATCS). This system allows the human train operators to supervise while the train drives itself. But, it only works on the subway, or underground, portions of the trains’ routes. That’s because of the loop cable, which transmits the data between the central servers and the trains. It’s as old as floppy disks, “has less bandwidth than an old AOL dial-up modem,” and is too fragile to extend above ground.

Fortunately, SFMTA is in the midst of a “complete overhaul of the current train control system and all its components, including the onboard computers, central and local servers, and communications infrastructure.” The floppy disks are on their way out, but it’s a huge undertaking that was slowed due to the COVID-19 pandemic, and completion isn’t expected until the end of the decade. So for now, it’s all still riding on the floppy disks.
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