A new provision in federal law could shut down the train service in New Jersey, says New Jersey Transit. There is a Dec. 31 deadline to install Positive Train Control systems, which would stop a train that is speeding or doesn’t follow signals. The agency says it has budgeted for and plans to have the systems fully in place by 2018 but would have to cease operations if the law isn’t changed. The Positive Train Control was mandated after a 2008 crash in California.