how to make bridges invurnerable?

[darkreapers]

i have a bridge that connects 2 important part of the map, however during game play it can be destoried from effects of spells. how do i make bridges invurnerable?

 

[Samlag]

Try, Object Editor > Destructibles > Bridges/Ramps > (You'r Bridge) and check Combat - Target as: Bridge + Invurable.