This is the east entrance to the Mount Carmel Tunnel, as seen from the Canyon Overlook Trail. The tunnel is one mile in length and follows the contour of the mountain.....way cool! It was built in 1929. The Tunnel has five openings (like eyelids) which allow natural light (not much) and fresh air to seep in. There are no lights in the tunnel. When a Bus or other large vehicle comes through, traffic is halted in the opposite direction, allowing the vehicle to travel through the tunnel by itself (long with any other vehicles behind it). The reason being the vehicle has to straddle the center line to not hit the tunnel walls.