Board Thread:Questions and Answers/@comment-88.108.15.1-20140310101532/@comment-24572452-20140311221529

You can't. There's no perfect "key" for a train. The formation of the train (the value) depends on your own demands. Even the length of the train is no benchmark. The only thing you can do is to make a trainformation and look at the timetable what it's worth. Good luck.