hi-rail-pant, you say? Only reason I could think of for having that "-pant" on the end is if it's a pantograph, in which case it requires an asset which uses it for it to appear--we must remember, content creators have found more things to do with the panto. function than you can shake a stick at!
If it'sa pantograph then it's a dependency itself and you need to download the traincar it goes to. In this case it's called the hy-rail, a model of a Western Star semi tractor fitted out to transfer between road and rail.
50567:15015
Click on the "view pack" and grab everything.