A vehicle enters the Anton Anderson Memorial Tunnel, North America’s longest combined rail-highway tunnel.
Whittier Tunnel is just 16 feet wide and has a single lane shared by both rails and cars. Rail and road traffic are coordinated by two sophisticated computer-based systems which control the timing of vehicles entering the tunnel, spacing them for safety, and lower railroad gates when a train is approaching. Cars heading to Whittier are allowed every half hour while cars leaving Whittier can enter the tunnel every hour. In between regularly scheduled passenger trains are also accommodated.
The tunnel interior is exposed to the natural rock - only portions of the tunnel are lined with concrete and steel. The majority of the tunnel has a wire mesh attached to the ceiling to catch any loose rocks that could work out over time. Inside the tunnel there are several "safe-houses", which are small buildings that are used in case of severe earthquakes, vehicle fires, or other emergencies. The tunnel also contains several turnaround spots, which are reserved for disabled vehicles.
Fresh air is pumped into the tunnel using a combination of conventional portal fans and reversible jet fans which look like pretty much like aircraft jet engines.
The tunnel's entrance portals are designed in an A-shape, with a large, train-sized "garage door", which allows traffic in and out of the tunnel. As many as 450 vehicles can wait outside for passing through.
A southbound train exits the Anton Anderson Memorial Tunnel. Northbound vehicular traffic can be seen lining up, waiting its turn to head back through the tunnel toward the Seward Highway.
The 2.5 mile long tunnel has eight safe houses, which can provide refuge during an emergency.
Tunnel control operator Daniel Gutierrez monitors traffic from 60 video cameras at the tunnel control center on Thursday, June 19, 2014. All tunnel operators are also firefighters trained to respond to an accident inside the 2.5 mile long tunnel.