NEWARK, N.J. (CBSNewYork/AP) — Starting next month, NJ TRANSIT riders will have to deal with schedule and other changes as service is reduced for months to speed up installation of a new safety system.

NJ TRANSIT is supposed to have a crash prevention system, called positive train control, installed on all of its trains by the end of the year.

The federal government mandated the system on all commuter trains by Dec. 31. But through the end of 2017, NJ TRANSIT reported it had only 35 of 440 locomotives equipped with the system and hadn’t finished installation on any of its 11 track routes.

Last week, the Federal Railroad Administration sent a letter expressing concern that NJ TRANSIT would miss the deadline to install the system.

That means NJ TRANSIT will have to reduce service as it works to install the system on its tracks and cars, mostly impacting customers on the Northeast Corridor, North Jersey Coast Line, Morris & Essex and Pascack Valley lines

Starting next month at certain times, trains will be discontinued and train stop locations could change, lasting until at least the end of the year.

“Often times there are already delays, so I think it will be a little bit challenging,” one commuter said.

“Will have to make adjustments at work,” said another.

And it’s not just the system that needs to be installed. Employees also have to be trained. Rail expert Robert “Buzz” Paaswell doesn’t believe there will be too much of a noticeable disruption to service.

“The installation and testing could take up to a month with all the testing and back and forth,” he said. “It’ll be an annoyance perhaps sometimes or you’ll rush to get your usual train going home and it’s not there, but you’ll realize that in the long run, this is going to prevent accidents so it’s worthwhile.”

He also doesn’t believe NJ TRANSIT will made the deadline that was already pushed from 2015 to 2018.

PTC is an emergency braking system that stops a train if it’s going too fast. In the aftermath of a 2008 commuter rail crash in California that killed 25 people, the government required commuter and freight railroads to have the system installed.

NJ TRANSIT could get a two-year extension to finish installing PTC if it meets certain benchmarks by the end of the year, such as installing all system hardware and completing employee training. But even that is in doubt, according to last week’s FRA letter.

Last month, NJ TRANSIT Executive Director Kevin Corbett said an overnight test of the system on tracks in Morris County had been successful and that he was more confident than he had been when he assumed the position a month earlier. But he stopped short of saying NJ TRANSIT would meet the 2018 deadline.

“We are doing everything in our power to install this important safety technology as quickly as possible,” Corbett said in an email Thursday. “I ask for customers’ patience during this process as the end result is a safer railroad for everyone.”

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(© Copyright 2018 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)