Once upon a time, railroads used to employ more people and some of those people would patrol the track during times of severe storms, either on motorcars or hi-rail vehicles, to examine conditions and make assessments as to whether or not it was still safe to run trains.

That arrangement was expensive and the railroads have since "cut corners" by relying on various weather reporting services to stay abreast of operational conditions during inclement weather. They also use the crew members of trains running through the area to make assessments of the track conditions. I would imagine the engineer and conductor, after they found an operational radio in the wreckage and mud of the derailed train, called the dispatcher and advised him or her that it was time to halt rail traffic through that area.

Like I said, the "old method" was probably better, but it was expensive. We now live in a different world.

This kind of stuff happens when Wall Street bean counters attempt to "play trains".