I think Ben Dorsey made something like that where the roads go underneath. There are also some bridges like this by some German content creators, but these are very urban-like bridges, again I can't think of the authors the exact assets offhand.
Anyway. What exactly do you need? This might help narrow down the critter.
Do you have any pictures of a prototype?
If needed, you can always construct something like that by laying a road spline on the railroad bridge. A single track bridge is about the same width of a YARN road and with the YARN roads the rails will stick up through the surface nicely . With this setup, you can use the ATLS system to stop the road traffic before a train crosses.
The alternative is to use a double track bridge and occupy a track with a road for a single track setup. Set the road slightly higher than the track so that the road is buried. YARN roads are good this way too because they're thick enough to bury the tracks. For a wider combo-bridge, the road could occupy a track while the remaining track line occupies the rest of the bridge. If you want to get fancy, you can go as far as to put in a fence or chain-bollard between the rails and the road.
Hope this helps.