Pretty sure they're using a speed/distance graph, but I seriously don't have a clue what's happening there XD I think a speed/time graph would be more informative though, as it would show how long you're stopped at stations. But yes, it could seriously do with some units down there. Same goes for the gradient graph as it's not too useful without knowing just how steep the inclines you are facing are, but I know many people have mentioned this already.