Pathing on ramps and bridges

I thought if you placed a bridge over deep water it immediately became pathable, but on my current map this doesn't seem to be the case. So I had to create shallow water ( woth ramps) under the bridge before my units could cross it. Does it have to be this way?

eh when i make a bridge it becomes pathable...did you check the pathing map its using?

Check to see if the bridge has Pathing - Is Walkable (Checked).