Max speed is 40 mph according to a few websites I saw. But the tracks are not in great shape.
I found a page about trains in the Cache County area. Here is the bit about Hyrum:
"Hyrum Utah is home to E.A. Millers meat packing plant & stockyards. This must have been a busy
place for the railroad at one time, but now most every thing is hauled in or out on trucks.
The train still switches here & will spend about an hour doing their work when work is needed.
I'm working on getting more photos here. The line made a northward curve on the east side of
the packing plant & heads north for the first time since leaving Cache Junction."
The Cache Valley Branch
I don't think the line between Logan and Hyrum has very regular service, so this may not be a fruitful course for further sleuthing.... other than my contention that it would still be a good route to take if you were walking to Hyrum and didn't want to be seen