Tanks Crossing Rivers?

I'm trying to build a mission where tanks must cross bridges in order to advance. If the bridges are destroyed I want the tanks to get stuck on the other side, but they just drive through the bridge wreckage or through the water.

Is there a way to forbid them from crossing if the bridge is destroyed?

I haven't done much with complicated ground battles in a while but if I remember there is a stop function in the triggered actions for ground vehicles. You'd want to detect the bridge destruction, then use this to trigger the stop action.

Set up a trigger that detects if the bridge is destroyed (if you can't check the bridge directly place a static object or small unit or something on the bridge and use that instead). One the trigger condition is met, set it to AI Task Push the stop command.