Buff and Draft problems

please forgive me if ive got the terms wrong. After watching a program about a coal train on discovery channel i became interested in these opposing forces, i understand the concept completely, my question is, does RW portray this realistically ? i set up a train with the same amount of wagons as a train i randomly found in Google Earth, and after a quick measurement i found it to be over 1.5 miles long, i may be out by a few meters, but still, this is collosal compaired to the longest trains we have over in Britain, anyway, i proceded to test this train on a quick test track i set up, basically flat and about 5 miles long, it took a while to get moving but once it did i was able to pick up speed quite quickly, this seamed wrong for a start, and on coming to a complete stop and releasing the brakes i shot forward up to a speed of 31MPH, even tho i only reached 15 during the test, does this happen in real life? and if so how do you control it?