For years I have said that I would love to see more rail and less truck transportation. It just won't happen. Wade did an excellent job of pointing out why not.
Other factors are
taxes. States get a boat load of taxes off of over the road truckers. If truck traffic dried up so would road funding.
Oil. If there is less truck traffic there is less fuel oil consumed. Oil companies don't like that idea and tell their goverment reps that.
The delay factor is incredible. I worked at a local plant when I was in college. Most of the supplies coming in were trucked in a few came on rail cars. Most of the finished goods went out on truck with a small few by train.
The train load had to be a lot larger. It had to go to one customer only. We had to do extra work to secure the items being shipped so that they wouldn't shift around on the train which is a much rougher ride. (Roughly double the rocking and shaking of a truck.) Then we had to wait for the train to come and pick it up when it fit their schedule. The orders were not across country they most often were from northern Illinois into central Wisconsin.
Keep in mind that this was all before cargo containers florished. It is possible to ship a smaller quantity today. But the rocking of the loads may well be greater for the containers on top.