They used floppy disks for 26 years. The metro is finally modernizing
It’s a bit hard to believe that floppy disks are still in circulation and that they are used to control infrastructure as crucial as subway trains. One of the largest metro networks in the world has decided to modernize it for USD 212 million.
5.25″ floppy disks and DOS – the heart of the train control system
Since 1998, Automatic Train Control System (ATCS) in subway station in San Francisco used three 5.25″ floppy disks loaded with DOS-compatible software that controlled central rail control servers. When the train enters the subway, the computer connects to the ATCS system and switches to automatic mode, when the operator stops driving the train and only supervises its work. In turn, when a train leaves the subway, it disconnects from ATCS and switches to manual mode, at which time trains run on the streets.
Now 26 years later, the San Francisco Municipal Transportation Agency (SMFTA) has decided to modernize its aging infrastructure.. This is because the system, introduced in 1998, was designed to last for approximately 20-25 years, which means that it has already become objectively obsolete in 2023, although it is still operational. But due to the fact that floppy disks are at risk of data degradation, and it is no longer difficult to maintain specialists’ proficiency in programming languages from the 1990s – the authorities of San Francisco decided to make changes. It is also worth emphasizing that not only floppy disks are a problem. A spokesman for the San Francisco Rail Transit Authority, Michael Roccaforte, emphasizes that delicate cables are also a problem and “have lower bandwidth than the old dial-up models” (56 kbps – editor’s note).
San Francisco’s subway system needs much more than just software upgrades. SMFTA signed a $212 million contract with Hitachi for 20-25 years of support to introduce modern software, replace cables with Wi-Fi and cellular signals to track train routes by the end of 2028. The US office will spend a total of up to $700 million on all modernizations.
The San Francisco subway was not the only organization that continued to use floppy disks. In Japan, this practice was discontinued in government institutions only in June 2024, and the German Navy is still wondering how to replace the 8-inch floppy disks in the Brandenburg F123 frigates.
