The train was heading into Manhattan at around 10:19 a.m. when a vital piece of equipment detached, causing the emergency brake to activate and halt the train between High Street and Fulton Street stations, MTA spokesman Tim Minton said in a statement.
The breakdown completely derailed A and C service into the afternoon and sent firefighters rushing into the station in response to smoke that billowed through the tunnel — a result of "some sparking" that occurred during the breaking process, Minton said.
Commuters on board were ushered onto a rescue train that shuttled them back to High Street. The transit authority momentarily cut power to the tracks around 12:30 p.m. to remove the troubled train from its location. A and C trains were forced to hold in stations in Brooklyn and Queens at that point and, after a series of reroutings and delays, normal service was restored by 1:06 p.m.
The MTA determined that a current collector on the train — a part that connects train cars to the electrified third rail, also known as a "shoe" — had fallen off. Ultimately 19 trains were delayed and another 45 experienced service changes, with impacts rippling across seven lines, according to an internal incident report obtained by amNewYork.
"The cause of its detached shoe is under investigation," Minton said. "Crews inspected the track area for defects, finding none. A test train subsequently operated through the same tunnel completing its run without encountering obstructions."
The line is served by the oldest trains still in service: the R32s. The model first started rolling on the city’s rails 55 years ago and frequently breaks down. But Sunday’s incident involved a newer R179 train model.