Railworks America

I have been working on a highly detailed route for over a year and a half, and finally started a free roam activity in my main rail yard. I have been having problems with the game crashing when placing locomotives and rolling stock to fill my yard. I have a nice rig so my computer is not lacking in any way, but im thinking its something internal with the game. I can travel to the yard with no problem, but this activity.... Could it be a corrupt activity?