Bridges

Are there any way to make bridges crossable both by over and under

I really need this and I don't mind if it requires JASS or modelling

btw, don't tell me to put something with waygate and stuff

The simple answer - No

The complex answer - Yes

If yo plop down some waygates to effect pathing only, then when a unit somes near the bridge, disable its control and pathing and order to to the other side. Then re-coltrol and path.