What WH has posted on 11/7 is exactly why the Wyoming G&F will no longer cite people for corner jumping. The head honchoes in Cheyenne directed the field employees, who all have a Garmin GPS with map chips, not to investigate corner jumping complaints after they lost a case a few years ago in court when a guy pled not guilty to trespassing. However, as WB mentioned in his post, you need to be aware of whether the County Sheriff in the county you are hunting will cite you for it. It also goes a little further than that in that if you are issued a ticket for trespassing in a corner jumping situation and enter a not guilty plea instead of paying the ticket, it is then up to the County Prosecutor to handle the case. Some will handle the case, while others will not, and if the Sheriff knows that he will normally not have his personnel cite you because of the chance of a person taking it to court and the case being dropped. Therefore, in Wyoming it is best to approach the local Prosecutor and find out their position on corner jumping in their county BEFORE each hunting season. Since these persons may move on to other positions it is necessary to make sure they are still in charge BEFORE you hunt each year so you don't get nailed because it's up to the individual in charge as to how they want to handle corner jumping. Having hunted in Wyoming most years since 1994, I'm pretty well up to speed on this issue and how to handle it if you plan on hunting any area where you may want/need to corner jump to access a piece of public land.
As far as the RR issue, that is private property and if you cross the tracks without permission, which will probably not be given due to a lawsuit possibility in case of an accident, it would be the same as going directly across any other piece of private property without permission. People get away with it because there are no RR personnel handling that type of issue with the miles of tracks they would have to be watching.