it is almost impossible to get my men to stand on the bridge or cross it. does anyone else have this problem?

bridges were always this way in the game . the choke points are a must though i don't care for a map without a river I. always set a patrol a block down or up and work from there. Bridges do cause routing errors for your hoods so send them a block past the bridge to get them in the right direction.
As far as standing on a bridge the only way I can remember is in the weekly orders stage to send them to a specific spot.