I have put up 15 mph invisible speed limit signs but the locos still go about 20 at some points. Then the train slows and then go back up to 20 or higher. This is when its under AI control, and I cannot find out what is causing it. There is a long single straight section or track where the engine will run at the speed limit, but it seems that when the train crosses junctions it will go faster then the speed limit even if there is a limit sign right on the other side of the junction. I'm sorry if this isn't clear, it's late at night here and I'm tired from trying to get this to work...