“Why would anyone jog along a railroad track of an active rail line?”
Because people assume that they will hear or feel an oncoming train in plenty of time to get away from the tracks.
This is not always the case. An approaching train can be much quieter than you expect one to be. And if it is traveling at high speed you could be in a world of trouble.
In Collierville, TN. where my ex wife and kids live, runs a very active Union Pacific (I believe) rail line...been there since before the Union Forces tore up sections during the Civil War.
Anywho...beside the old train depot is a viewing platform where you can stand just a few feet off the main line as the trains blow past. It is crazy how quiet and smooth the train is as it passes by blowing your hair in its wake.
With continuous welded rail, etc...trains are freaky quiet.