No, the owner of the freight car (a tank car I believe) that suffered a hot box is the one with primary liability. Most railway tank cars are own not by a railroad but a carrier group such as GATX.
“A hot box is the term used when an axle bearing overheats on a piece of railway rolling stock.”
https://en.wikipedia.org/wiki/Hot_box
“Most of the larger railroads use defect detectors to scan passing trains for hot box conditions. Some of these detectors also have ‘automated mile posts’ which send an automated radio signal to the train crew listing the train number, track number, number of axles on the train and train speed.”
If “the owner of the freight car” knew of the defect, they would have primary responsibility I believe.
Norfolk Southern is liable as well. They are the company owner, any carrier is a contractor and hired/paid for NS, therfore, they have direct liability.
A “hot box” goes back to the days before roller bearings on freight cars. Can’t understand this as a cause.