The Leonard P. Zakim Bunker Hill Memorial Bridge (or Zakim Bridge) is a cable-stayed bridge

Cable-stayed bridge

A cable-stayed bridge is a bridge that consists of one or more columns , with cables supporting the bridge deck....

 across the Charles River

Charles River

The Charles River is an long river that flows in an overall northeasterly direction in eastern Massachusetts, USA. From its source in Hopkinton, the river travels through 22 cities and towns until reaching the Atlantic Ocean at Boston...

 in Boston

Boston

Boston is the capital of and largest city in Massachusetts, and is one of the oldest cities in the United States. The largest city in New England, Boston is regarded as the unofficial "Capital of New England" for its economic and cultural impact on the entire New England region. The city proper had...

, Massachusetts

Massachusetts

The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...

. It is a replacement for the Charlestown High Bridge

Charlestown High Bridge

The Charlestown High Bridge , spanned the Charles River in Boston, Massachusetts, and was part of Interstate 93 and U.S...

, an older truss bridge

Truss bridge

A truss bridge is a bridge composed of connected elements which may be stressed from tension, compression, or sometimes both in response to dynamic loads. Truss bridges are one of the oldest types of modern bridges...

 constructed in the 1950s, and is the world's widest cable-stayed bridge. Of 10 lanes, the main portion of the Zakim Bridge carries four lanes each way (northbound and southbound) of the 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...

 and U.S. Route 1

U.S. Route 1

U.S. Route 1 is a major north–south U.S. Highway that serves the East Coast of the United States. It runs 2,377 miles from Fort Kent, Maine at the Canadian border south to Key West, Florida. U.S. 1 generally parallels Interstate 95, though it is significantly farther west between...

 concurrency

Concurrency (road)

A concurrency, overlap, or coincidence in a road network is an instance of one physical road bearing two or more different highway, motorway, or other route numbers...

 between the Thomas P. "Tip" O'Neill Jr. Tunnel

Thomas P. O'Neill Jr. Tunnel

The Thomas P. "Tip" O'Neill, Jr. Tunnel is a highway tunnel built as part of the Big Dig in Boston, Massachusetts. It carries the Central Artery underneath downtown Boston, and is numbered as Interstate 93, U.S. Route 1, and Route 3. It roughly follows the route of the old elevated Central Artery,...

 and the elevated highway to the north.