In spite of the Turnpike Commission dubbing the new road "The World's
Greatest Highway", the Turnpike was
popularly known as the " Tunnel
Highway". Many souvenirs promoted the
original stretch's seven tunnels through Pennsylvania's
Appalachian Mountains. These tunnels, from
east to west, bored through Blue Mountain, Kittatinny
Mountain, Sideling Hill, Ray's Hill, , and Laurel Hill. Allegheny Mountain
Above: The Bankhead Tunnel runs underneath the
Mobile River in Alabama.
The tunnel was built in sections and floated to the proper positions, then
sunk. Each section was sunk next to the previous section and joined underwater. Only
passenger cars and pickup trucks are still allowed to travel through the
tunnel, as it is very narrow.
Construction of the Liberty Tunnels began in 1919. The boring of the 5889 foot tubes was completed in 1922. When the Liberty Tunnels were opened to traffic in 1924, they were considered an engineering marvel. The nearly two-mile span was the longest tunnel in the country at that time.