Home Tech San Francisco’s train system still uses floppy disks, and will for years

San Francisco’s train system still uses floppy disks, and will for years

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San Francisco's train system still uses floppy disks, and will for years

The San Francisco Municipal Transportation Agency, which runs the city’s Muni Metro light rail, claims to be the first American agency to adopt floppy disks. But today, the SFMTA is eager to abandon its reliance on 5¼-inch floppy disks; just give it about six years and a few hundred million more dollars.

SFMTA members recently spoke with the ABC7 Bay Area News and detailed the agency’s use of three 5¼-inch floppy disks each morning. The floppy disks have been part of Muni Metro’s Automatic Train Control System (ATCS) since its installation at a Market Street subway stop in 1998. The ATCS has multiple components, “including onboard train computers that are connected to propulsion and braking systems, central and local servers, and communications infrastructure, such as loop signal cables,” SFMTA spokesperson Michael Roccaforte told Ars Technica.

The floppy disks are used to load the software that runs the central servers, Roccaforte said:

When a train enters the subway, its onboard computer connects to the train control system to operate the train in automatic mode, where the trains drive themselves while operators supervise. When leaving the subway they disconnect from ATCS and return to manual operation on the street.

Roccaforte said initial planning for an ATCS overhaul, including moving away from floppy disks, began in 2018 and was expected to take a decade from initial planning to completion. Due to an 18-month pause related to Covid-19, it is expected to be completed between 2029 and 2030. SFMTA expects to decide on a contractor in early 2025 and will then release a detailed project schedule.

“Ultimately, our goal is to have a single train control system for the entire rail system,” said Jeffrey Tumlin, SFMTA transportation director. ABC7.

Floppy Disk Defects

“If it ain’t broke, don’t fix it,” some say. But while the floppy-disk-based train control system is currently working, there are challenges in relying on the outdated technology, which the SFMTA has highlighted for years.

the transport body says The train control system was built to last only 20 to 25 years, meaning it will exceed its expected useful life in 2023. In 2020, the Muni Reliability Working Group, which is said to be made up of transit experts local and national, recommended replace the traffic control system within five to seven years.

When asked how “terrible” it is to upgrade from floppy disks, Tumlin said ABC7 that everything is a matter of risk.

“The system currently works well, but we know that each year the risk of data degradation on floppy disks increases and that at some point there will be a catastrophic failure,” Tumlin said. ABC7.

Previously, the transportation agency stated that ATCS had become more difficult and expensive to maintain over time. He has also discussed the challenges he has finding workers who know how to use the date system.

“We have to maintain programmers who are experts in the programming languages ​​of the ’90s in order to continue running our current system, so we have technical debt that goes back many decades,” Tumlin he told San Francisco’s KQED in February 2023.

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