I agree with CKorfmann. The tower has to be on its foundation, and the bridge has to connect to the road, so neither can be moved to accomodate the other.
I have reconsidered this and now agree with CK. Whichever feature is there first trumps the other. Neither one is entitled to exist if the other is already there. If a bridge is built before the tower gets to section two then the tower is stopped at section one. If the tower if built to two sections the bridge cannot be built. This is a reasonable conclusion.