NJ Transit will restore rail service on the Atlantic City Line in the spring, the agency said Friday.

The agency had temporarily suspended trains between Philadelphia and Atlantic City in September in an effort to meet federal safety requirements by the end of 2018.

Though the agency had anticipated being able to bring the trains back as early as this month, it faces a continued shortage of locomotive engineers and lingering effects of the effort to install positive train control by Dec. 31.

The Federal Railroad Administration must approve NJ Transit's work on that safety system, and because of the partial government shutdown, most of the federal regulator's staff had been furloughed.

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NJ Transit will extend the 25 percent discount on alternative bus service it has offered since September for Atlantic City riders until rail service is restored.

The agency also said it would continue the bus substitute for the Princeton Junction to Princeton Dinky train until the spring.

"Our goal is to begin restoring a service that remains reliable and predictable for customers as quickly as possible,” said Executive Director Kevin Corbett in a statement. “I share our customers’ frustration and thank them for their continued patience during this time."

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NJ Transit riders have endured months of service frustration, with overcrowded, delayed and canceled trains.

The work on positive train control was partly to blame. The agency has also scrambled to hire new locomotive engineers.

Last week, it said that 102 student engineers were enrolled in six training classes. Those candidates will graduate starting in the spring and continuing into the fall and next year.