Please be careful about how to mark a bridge. There must be two nodes(节点) on two sides to separate(分割) the line if you want to make a bridge, or the whole routh will be a LONG bridge. 
Also be careful about how road intersections are made. When two lines across, a node must be use to connect them together. They shouldn't directly overlap.
You can recheck the amended version of G316 to learn how to make bridge or intersections~