>>138723653D modeller fag here.
The bridge appears to be not using the alpha map assigned to it to make the arches opaque. If you compare the two pictures you can see the arches are drawn onto a a rectangle (plane) and then the brown surrounding it. The brown part is supposed to be invisble but I'm guessing it was just a bug with the recording software or something. Will most probably be the first picture we get in game. Check the pic for what alpha mapping is.