I drive by a Batch plant every day that unloads the Sand and Gravel from Rail cars a couple times a week. They use a large Track Hoe and they crawl up on the cars much like these pictures with out the guides though. Believe it or not he mounts from the side of the car then turns 90' to move the length of the cars while unloading.
Heck of an operation because the plant is on the opposite side of a busy highway and they have to pile up big piles of aggregate and then load it on to trucks and haul it across the road to the plant.