The Anton Anderson Memorial Tunnel (often referred to simply as the Whittier Tunnel) is a tunnel through Maynard Mountain in the U.S. state

U.S. state

A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...

 of Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

. It links the Seward Highway

Seward Highway

The Seward Highway is a highway in the U.S. state of Alaska that extends 127 miles from Seward to Anchorage. It was completed in 1951 and runs through the scenic Kenai Peninsula and Turnagain Arm, for which it was designated an All-American Road by the U.S...

 south of Anchorage

Anchorage, Alaska

Anchorage is a unified home rule municipality in the southcentral part of the U.S. state of Alaska. It is the northernmost major city in the United States...

 at the former town of Portage

Portage, Alaska

Portage is a former settlement on Turnagain Arm in Alaska, about south of Anchorage. The town was destroyed almost entirely in the 1964 Good Friday Earthquake when the ground in the area sank about six feet, putting most of it below sea level. All that remains today are the ruins of a few...

 with the relatively isolated community of Whittier

Whittier, Alaska

Whittier is a city in the Valdez-Cordova Census Area, in the U.S. state of Alaska. As of 2006, the population was 177. The city is also a port for the Alaska Marine Highway.-Geography:...

, a port for the Alaska Marine Highway

Alaska Marine Highway

The Alaska Marine Highway or the Alaska Marine Highway System is a ferry service operated by the government of the U.S. state of Alaska. It has its headquarters in Ketchikan, Alaska....

. It is part of the Portage Glacier Highway and at 13,300 feet (4,050 m), is the second longest highway

Highway

A highway is any public road. In American English, the term is common and almost always designates major roads. In British English, the term designates any road open to the public. Any interconnected set of highways can be variously referred to as a "highway system", a "highway network", or a...

 tunnel

Tunnel

A tunnel is an underground passageway, completely enclosed except for openings for egress, commonly at each end.A tunnel may be for foot or vehicular road traffic, for rail traffic, or for a canal. Some tunnels are aqueducts to supply water for consumption or for hydroelectric stations or are sewers...

 and longest combined rail and highway tunnel in North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

.

The original tunnel was completed in 1943 and used for railroad traffic. In the mid-1960s, the Alaska Railroad

Alaska Railroad

The Alaska Railroad is a Class II railroad which extends from Seward and Whittier, in the south of the state of Alaska, in the United States, to Fairbanks , and beyond to Eielson Air Force Base and Fort Wainwright in the interior of that state...

 began offering a shuttle service for automobiles, similar to Amtrak

Amtrak

The National Railroad Passenger Corporation, doing business as Amtrak , is a government-owned corporation that was organized on May 1, 1971, to provide intercity passenger train service in the United States. "Amtrak" is a portmanteau of the words "America" and "track". It is headquartered at Union...

's Auto Train

Auto Train

Auto Train is an scheduled train service for passengers and their automobiles operated by Amtrak between Lorton, Virginia , and Sanford, Florida . Although there are similar services around the world, the Auto Train is the only one of its kind in the United States...

, which allowed vehicles to drive on to rail cars to be transported between Whittier and the former town of Portage. As traffic to Whittier increased, the shuttle became insufficient, leading in the 1990s to a project to convert the existing railroad tunnel into a one-lane, combination highway and railroad tunnel. Construction on this project began in September 1998, and the combined tunnel was opened to traffic on June 7, 2000.
As eastbound traffic, westbound traffic, and the Alaska Railroad must share the tunnel, rail and road traffic are coordinated by two sophisticated computer-based systems: the Tunnel Control System and the Train Signal System. As reflected on the Alaska Department of Transportation Tunnel Website, it is now considered "North America's longest railroad-highway tunnel." The tunnel held the title of the longest road tunnel in North America (at nearly 2.5 miles [4 km]) until completion of the 3.5 mile (5.6 km) Interstate 93

Interstate 93

Interstate 93 is an Interstate Highway in the New England section of the United States. Its southern terminus is in Canton, Massachusetts, in the Boston metropolitan area, at Interstate 95; its northern terminus is near St. Johnsbury, Vermont, at Interstate 91...

 tunnel as part of the "Big Dig" project in Boston, Massachusetts. It was a 2001 recipient of an Outstanding Civil Engineering Achievement Award from the American Society of Civil Engineers

American Society of Civil Engineers

The American Society of Civil Engineers is a professional body founded in 1852 to represent members of the civil engineering profession worldwide. It is the oldest national engineering society in the United States. ASCE's vision is to have engineers positioned as global leaders who strive toward...

.

The tunnel is named after Anton Anderson

Anton Anderson

Anton Anderson was chief engineer of the Alaska Railroad and served as Mayor of Anchorage, Alaska from 1956 to 1958. He has been called "Mr. Alaska Railroad".-Biography:...

, an army engineer who in 1941 headed up the construction of the railroad spur from Whittier to Portage.