I have not seen too many railway bridges on this forum, let alone bridges that move! This MOC is not quite a common type of moveable railway bridge either, it's a double-leaf drawbridge. More common would be a bascule bridge. The difference being that a bascule bridge has it's contraweight either directly below the (rail)road or above it, but then directly attached to the bridge deck. The double-leaf drawbridge has a contraweight attached to a 2nd structure above the road. The nice thi