I think it could be very interesting to have pre-built bridges, and you're given a budget with which to take the bridge down. You can spend the budget on various explosive charges, and figure out where best to place them that will destroy the most of the bridge. You could have restrictions on how many pieces are left intact to be hauled out of the river and such. Sounds interesting.

I agree with mendel on this one; it would be about bridge demolition, not terrorists trying to blow up the bridge. Not everything that explodes needs to be on CNN 24/7.