The tunnel from Whittier is one way traffic...this tunnel is fascinating check out some of the interesting facts...
Fifty miles southeast of Anchorage near Portage Glacier, the tunnel connects the port city of Whittier on Prince William Sound to the Seward Highway and Southcentral Alaska. It opened to vehicle traffic on June 7, 2000 after extensive conversion from a World War II railroad tunnel.
Longest highway tunnel in North America (13,300' or 2.5 miles).
Longest combined rail and highway use tunnel in North America.
First U.S. tunnel with jet turbine and portal fan ventilation.
First computerized regulation of both rail and highway traffic.
First tunnel designed for -40 F. and 150 mph winds.
Portal buildings designed to withstand avalanches