The seventh patch for SimCity adds in a neat feature that is sure to please long time fans of the franchise who have also stuck with EA’s much maligned reboot for this long: lowering and raising terrain, specifically streets. The video above, which details how you go about it, shows how easy the process is this time; specifically, while you are laying down streets, you hold down the M key to raise the road six meters at a time; holding down N lowers the street six meters at a time.
You can make bridges and tunnels this way, and assuming you go high or low enough, you can make bridges that go over other roads, or tunnels that go under other roads. Feasibly, it should be possible to have a bridge over a road over a tunnel, but that is something someone with the game and this update will have to confirm for me.