HOBOKEN, N.J. — The train that slammed into Hoboken Terminal on Thursday, killing one person and injuring more than 100, ran its fateful final route with no functioning data recorder in the locomotive, making it impossible for investigators to gather valuable information on why the train crashed, a federal official said Sunday.

It was one of several NJ Transit equipment failures on board the train, as detailed Sunday by Bella Dinh-Zarr, vice chairman of the National Transportation Safety Board, which is leading the investigation. News of the broken data recorder comes after it was revealed that the Federal Railroad Administration fined NJ Transit in June for multiple safety violations, and that the administration is still monitoring NJ Transit’s performance.

The failed data recorder was built in 1995, Dinh-Zarr said.

“That’s quite an old event data recorder,” she said. “Usually when they’re not working, they’re replaced.”

Despite those equipment failures, the train may not have been speeding at the time of the accident. Thomas Gallagher, identified as the train’s engineer, told investigators that he was traveling 10 mph as he entered the station, within normal limits. That may contradict some early news reports, which quoted passengers and eyewitnesses who said the train was moving quickly when it crashed.

Investigators hope to confirm the train’s speed by accessing a second data recorder located in the front car, where Gallagher was standing as he drove the train. Federal rules require every train to have a functioning data recorder in its lead car, whether it’s a passenger car or a locomotive, said Jim Southworth, the investigator in charge of the inquiry. He did not directly state whether or not NJ Transit was in violation of federal rules by running a train with a non-functioning recorder in the rear, where the train’s locomotive and failed black box were located.

While the broken black box dates to the mid-1990s, when the locomotive was manufactured, the lead car was built in the early 2000s, Dinh-Zarr said, possibly increasing the likelihood that its black box is newer and still functional.

Train 1614 normally has five cars, but on Thursday it ran with just four, the vice chairman said. In a letter sent by NJ Transit in September to officials in Rockland County, the agency stated it was running shorter trains due to mechanical problems with many of its cars.

Because of this practice “this car was very overcrowded,” Dinh-Zarr said. “It was so crowded that the conductor was unable to collect the fares.”

It was unclear whether the overcrowding played any a roll in the accident, other than squeezing more people into the train’s lead car, which experienced severe damage during the crash.