Just over a decade after the debut of a costly, high-tech key subway signal system in Brooklyn, the MTA is readying a complete do-over.

Budget documents for a $7 billion plan to modernize subway signals over the next five years show that the authority is set to spend $47.4 million to replace a problematic signal system at the Bergen Street stop on the F and G lines.

That’s after paying $47 million for what was then the first-of-its kind computerized signal system in the subways when it was installed in 2006.

“That’s pretty ridiculous that they already spent a large amount of money and it’s still not working as it should,” said Alexandra Ilyashov, 31, who was waiting Thursday for the F at Bergen Street.

The computer-based interlocking system, which controls the signals and switches that guide trains through a network of tracks near Bergen Street, has been a persistent trouble spot for riders on the F and G lines that merge there.

In September, the F had a 66.8% on-time performance — the second worst-performing among all subway lines.

An MTA investigation last year flagged the factors behind the repeated problems, following a March 15, 2018, meltdown involving the Bergen Street signal system that caused six-plus hours of massive delays on the F and G lines, rippling to the A, C, D, E and M.

An internal incident report obtained by THE CITY showed “field element controller failure” at the Bergen Street interlocking led to 211 service changes on the F and G lines alone.

Learning from the Past

While the MTA pledged to find “long-term solutions,” the interim fixes included posting troubleshooting staff at the Bergen Street stop around the clock, tweaking the system’s circuitry and temporarily suspending service on multiple occasions to perform maintenance.

“The Bergen Street interlocking was installed as a pilot, so if that pilot failed, the right thing to do is replace the technology,” said Jaqi Cohen of the Straphangers Campaign. “But riders need to know new technology will operate differently in order to trust that the MTA is not throwing good money after bad.”

The computer-based interlocking at Bergen Street was part of a test program that began several years after a 1999 control-room fire at the station destroyed critical switching equipment. The system was manufactured by Thales, a French aerospace, transportation and defense giant.

Representatives from Thales did not immediately respond to requests for comment. An MTA spokesperson noted that crews remain on standby near the Bergen Street interlocking, in case of problems.

While it was the first of its kind in the New York subway, similar systems have since been installed elsewhere in the subway, including a pair along the No. 5/Dyre Avenue line in The Bronx.

Ben Fried of the advocacy organization TransitCenter said the problems with the Bergen Street system should serve as a cautionary tale for the MTA as it embarks on take two.

“If the solid state interlockings on the Dyre Avenue line are functioning reliably, it’s a good sign that they won’t repeat the same mistakes,” Fried said. “The whole episode highlights the importance of hiring and retaining people within the MTA with the chops to oversee new signal tech.”

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