A one-car Norfolk Southern derailment in Alliance, Ohio, turned a routine Tuesday morning into a traffic headache and an instant talking point in a national rail safety brawl.

Tramell Thompson, vice president of the transit workers union, said the MTA conductor remains rattled by the incident. “He’s afraid to get on the train,” he said.

The incident began when an off-duty Atlantic City officer intervened in what appeared to be a domestic dispute on the beach.

A 55-year-old man was injured in an altercation on a CTA Blue Line train on the West Side Wednesday morning, Chicago police said.