A road bridge that would allow trains under them.

I would be nice to have road bridges that allow trucks to go over 1-4 tracks. I hate that just to get truck to other side of track I either slowdown trains to either allow a crossing or to go up an incline. Trucks have no issue with a 25% incline to go over a bridge.

Have i got news for you. Captain's Diary #51 mentions bridges that could be manipulated into doing exactly what you'd want.
https://www.captain-of-industry.com/post/cd-51