I have no answer, but this got me thinking: is the overpass's road a similar physical width as the highway? I've been on some bridges that have two lanes with

I have no answer, but this got me thinking: is the overpass's road a similar physical width as the highway? I've been on some bridges that have two lanes with a very narrow shoulder that then then merge into a single lane (with wider shoulders) at the end of the bridge, with the asphalt width not changing too much. I've always assumed that was so traffic could continue flowing on the bridge should one lane become blocked for some reason. Off the bridge a car can pull off the road if there's a problem to let traffic continue passing. You can't really do that so much on a bridge. But I'm not a traffic/road engineer so that's just speculation on my part.