[kingkirbythe....]

Thats not what i was saying. I should have been more clear.

The bridge would have walls on both sides. The top would be open like a trench. Walking and biking paths would be cantilevered off the sides at the top of the walls. Or have the walking and biking path be over the top of the train and tracks. This would make the bridge a tunnel.

The like the trench version so the the walking path and the biking path could be more clearly separated. I guess the tunnel version could also have separated walking and biking paths too.