Sometimes the signalling will give a clue: Yellow means, "next one is red. Better slow down". At least in European railways, don't know about the US.
...edit... but sometimes even then it's not clear. There's a scenario in the Köln-Düsseldorf where suddenly you change tracks - and the switch can only be travelled at 40 Km/H - but the speed of the section is 100 or 120 or so.
This is not realistic of course. At a section like that, they would've installed a high-speed switch as well.
Last edited by Legend; 07/28/14 03:20 AM.