NEW YORK (CBSNewYork) — NJ TRANSIT is warning commuters that train service could grind to a halt at the start of next year.

An unthinkable act: stopping NJ TRANSIT would be paralyzing for thousands of commuters.

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Threatening that service might come to a screeching halt after Dec. 31, the railroad is sending a serious message to Congress to pass an extension of the deadline for positive train control — or else, WCBS 880’s Sean Adams reported.

NJ TRANSIT is still trying to install and test an emergency backup system that will automatically stop trains that speed or ignore signals.

NJ Transit said it was unclear whether they would be able to operate their trains come the new year, beyond that they would not elaborate, CBS2’s Alice Gainer reported.

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The federal government said without PTC the trains can’t legally roll and only Congress can change that.

Sources told CBS2 that trains will probably keep rolling and that NJ Transit will be fined heavily, which could result in fare hikes or service cuts.

NJ Transit issued a statement on Friday.

“Without a PTC extension, it is unclear whether NJ Transit will be able to operate passenger service as of January 1, 2016.”

Safety experts believe PTC could have prevented Amtrak’s deadly derailment in Philadelphia in May. It is designed to prevent derailments and collisions by automatically stopping a train that speeds or disobeys a signal.

CBS2 pressed NJ Transit to go on camera and explain what unclear means, but they would not.

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As it stands railroads operating trains on systems without PTC after the current deadline could face fines and other penalties.

So, was saying it’s unclear is it could operate just a scare tactic to help get an extension?

“The government says you should continue operating, the railroads don’t want to break the law, and so it’s now at a point where it’s lawyer versus lawyer,” rail expert Robert “Buzz” Paaswell said.

Paaswell said things will somehow get ironed out.

“In the long run, one says ‘A’ and one says ‘B’ and negotiation is probably at point ‘C.’ I suspect there are lawyers in a room somewhere right now looking at what the government wants done, what the railroads say they can do and some middle line will come out of all that,” Paaswell said.

At least one rider didn’t seem too worried.

“It’d be insane, the roadways would be stopped. The George Washington Bridge, all the arteries would be at a complete halt. It’s not possible not to give them the extension, I’m not too concerned,” Joe Farrell said.

The Star Ledger reported NJ TRANSIT expects full implementation by 2018. Meanwhile Amtrak is expected to meet the current deadline along the Northeast Corridor.

CBS2 reached out to the MTA who said they won’t be done until 2018 either.

On Friday, U.S. Sen. Cory Booker (D-N.J.) joined other lawmakers in asking Congress for a three year extension of the deadline, and where needed, financial assistance to get it done.

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A spokeswoman for NJ Transit said they are making good progress, but challenges remain.