I am sure this might apply to other bridge lengths too but the 4 tile wooden arched versions are not symmetrical on their slopes when planning. I have a screenshot below that highlights this more and both ends are the same height and level so i would expect that it should be symmetrical in the slopes it uses when planning. Now this might be a server issue more than model but put it here since it is a visual problem too. (if you feel it needs moved then please do) Now this might fix itself when building and i am going to test that but i am sure it will not. This might not seem like a big deal to some but to others this stops them from using the arched bridges they want. edit: Built bridge was the same..guess i am using all flat bridges