supersimpsons

Hi, I've had the NAM for a while with no problems, but I've been trying to have road overpasses over rail, and I've been using the road corner piece. Almost every time I use it, the game crashes either immediately or a short time after I plop it with no explanation. I have a custom train station near the bridge so I'm not sure if that has anything to do with it, but if anyone has any answers, that'd be great! Thanks.