NYC subway's modern train signals already due for upgrades

The subway system's modernization has taken so long that once cutting-edge technology for newer trains needs to be replaced.

Just after the dawn of the 21st century, the L train was the first subway line in New York City to get the technology, called communications-based train control, or CBTC.

The signal system uses computers to automatically drive trains, allowing them to run closer together at faster speeds.

The subway’s older signal systems, called “fixed block,” use mechanical equipment that in some cases dates back to the 1930s to prevent a train from getting too close to another one ahead.

MTA documents show that the CBTC system on the L will reach the end of its useful life in 2028, almost 25 years after it was installed. And although they're less efficient and prone to frequent breakdowns, the antiquated mechanical signals in use on many of the city’s train lines have lasted more than a century.

MTA officials have championed modern signals as a silver bullet to improve subway service. But the MTA's current timeline would install the technology on less than half the system over the next decade.

That the L train's CBTC equipment already requires upgrading highlights just how far behind the MTA is in modernizing the equipment relied on by millions of daily riders.

Sean Fitzpatrick, chief of staff at the MTA's construction department, said the system’s computer servers – known as “zone controllers” — that process information for trains in control and relay rooms need to be replaced.

He said the zone controllers, which are tasked with communicating and calculating a safe distance between trains, need to be upgraded to modern computers.

The radios on the trains could also be upgraded to wireless communications. And a software upgrade for both hardware components would be part of the replacement, according to Fitzpatrick.

“The basic premise is pretty straightforward: You’re probably not still using a laptop from 25 years ago,” Fitzpatrick said. “And so the computerized systems, especially, that were set up for CBTC on our first line, are reaching the end of their useful life and need to be replaced.”

He said any disruptions to service as the servers are upgraded will be “quite minimal.” The technology on the tracks themselves does not need to be replaced.

“This is a much more surgical impact,” Fitzpatrick said.

The MTA’s next five-year construction plan doesn’t specify plans to upgrade CBTC technology in place on other lines, including the entirety of the 7 line and sections of the E, F, G, M and R lines.

The construction plan does invest $5.4 billion into modernizing signals with CBTC on the Rockaway and Liberty lines for the A train and Rockaway S shuttle, parts of the J and Z line in Lower Manhattan and a major section of the N, Q, R and W trains from Astoria to Downtown Brooklyn.

Tracy Bowdwin, a consultant at engineering firm TYLin who worked for the MTA for over 30 years and was part of the team that implemented CBTC on the L train, speculated what upgrades the MTA might make for the replacement project.

“[The MTA] just prefers to change to an emerging technology, which is the train-centric CBTC where they don’t use the radio. They use telephone communications, 5G, to communicate with trains,” Bowdwin said.

He said it’s still premature to know what new technology the MTA will deploy for the L train project. He also said the long-term benefits of upgrading modern signals outweigh any short-term costs for riders.

“There is going to be some pain the ridership will have to bear, but at the end of the day, they’re getting a newer, more efficient, reliable train control system,” Bowdwin said.