I learned something while making a new bridge. These bridges do not like going over track that are on an angle to the tracks you’re building, even if it’s only 2 wide. I found it better to try and build your bridge perpendicular to the tracks you’re going over. It works better for some reason.
Also, from the image you posted, it looks like you are going from one hill to the next. Did you try to build a shorter piece coming from one hill? You might have to do that and build it in shorter pieces to work and it should work for you that way. I hope it does anyway/
Try to remove the track on the opposite side (destination) of your bridge. I usually get a collision i that situation because of the slope there: it can’t be modified to fit the bridge as a track is already blocking it.