First of all, nice work! The bridge is very impressive, especially the arch.
About the arch: could you tell me how you managed to build it? From the pics you posted I couldn't understand.
Maybe you could post come more detailed photos?
Thank you very much!
Finally finished! It was a really fun build and I'm pleased with the way it turned out. Except for some finishing touches and more specialized pieces, it was almost completely designed with Lego Digital Designer. This was a great help to minimize design and construction time.