Railworks America

when i try to bring up donnor pass all i get is a green and grey screen with no objects .just large squares and angles of color. all other routes work fine. also when i use continue for donnor, i get a screen with the diesels ,tracks and trees, but in place of foliage i get what looks like water. please keep answers simple,

I'd first suggest trying the "Verify integrity..." and "Clear Cache" procedures:
viewtopic.php?f=29&t=3905&p=36387#p36387

Make sure the in game settings are on High. The Detail level has to be at 10.