Twin bridges are a set of two

bridge A bridge is a structure built to Span (engineering), span a physical obstacle (such as a body of water, valley, road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over the obstacle, whi ...

s running parallel to each other. A pair of twin bridges is often referred to collectively as a twin-span or dual-span bridge. Twin bridges are independent structures and each bridge has its own

superstructure A superstructure is an upward extension of an existing structure above a baseline. This term is applied to various kinds of physical structures such as buildings, bridges, or ships. Aboard ships and large boats On water craft, the superstruct ...

, substructure, and foundation. Bridges of this type are often created by building a new bridge parallel to an existing one in order to increase the traffic capacity of the crossing. While most twin-span bridges consist of two identical bridges, this is not always the case. For a bridge owner, twin bridges can improve the maintenance and management of the structures. For motorists, twin bridges can limit the risk that both directions of traffic will be disrupted by an accident.

Examples

* Carquinez Bridge – original cantilever span built in 1927 and later twinned in 1958; a newer suspension span was built in 2003 to replace the original 1927 span, which was later demolished in 2007. *

Chesapeake Bay Bridge The Gov. William Preston Lane Jr. Memorial Bridge (informally called the Chesapeake Bay Bridge and, locally, the Bay Bridge) is a major twin bridges, dual-span bridge in the U.S. state of Maryland. Spanning the Chesapeake Bay, it connects the ...

– twin suspension spans with notable visual differences in construction techniques. *

Delaware Memorial Bridge The Delaware Memorial Bridge is a dual-span suspension bridge crossing the Delaware River. The toll bridges carry Interstate 295 and U.S. Route 40 and is also the link between Delaware and New Jersey. The bridge was designed by the firm o ...

– identical twin spans built 18 years apart from one another. * Maria Skłodowska-Curie Bridge – almost identical triplets. * Donald and Morris Goodkind Bridges – original

Art Deco Art Deco, short for the French (), is a style of visual arts, architecture, and product design that first Art Deco in Paris, appeared in Paris in the 1910s just before World War I and flourished in the United States and Europe during the 1920 ...

arch span built in 1929; newer steel bridge built in 1976. *

Crescent City Connection The Crescent City Connection (CCC), formerly the Greater New Orleans (GNO) Bridge, is a pair of cantilever bridges that carry U.S. Highway 90 Business (US 90 Bus.) over the Mississippi River in New Orleans, Louisiana, United States. The ...

– original cantilever span opened in 1958; parallel span opened in 1988 *

Lake Pontchartrain Causeway The Lake Pontchartrain Causeway (), also known simply as The Causeway, is a fixed link composed of two parallel bridges crossing Lake Pontchartrain in southeastern Louisiana, United States. The longer of the two bridges is long. The southern ...

– the longest twin-span bridge in the world. Original span opened in 1956, second span in 1969 * Bi-State Vietnam Gold Star Bridges – pair of cantilever bridges over the Ohio River. First span opened in 1932, second span in 1965. *

Blue Water Bridge The Blue Water Bridge is a twin-span international bridge across the St. Clair River that links Port Huron, Michigan, United States, and Point Edward, Ontario, Canada. The Blue Water Bridge connects Highway 402 in Ontario with both Interst ...

- Border crossing between Port Huron, Michigan (United States) and Sarnia, Ontario (Canada). * Québec Bridge * Sir Leo Hielscher Bridges * Iron Cove Bridge *

Tacoma Narrows Bridge The Tacoma Narrows Bridge is a pair of twin bridges, twin suspension bridges that span the Tacoma Narrows strait of Puget Sound in Pierce County, Washington, Pierce County, Washington (state), Washington. The bridges connect the city of Tacom ...

Daniel Carter Beard Bridge The Daniel Carter Beard Bridge (also known colloquially as the Big Mac Bridge), is a yellow twin span steel bowstring arch bridge crossing the Ohio River in Cincinnati, Ohio. It carries Interstate 471 between Cincinnati, Ohio, and Newport, K ...

* Tappan Zee Bridge – originally a single span in 1955, rebuilt into a new double span in 2017, old bridge demolished * Newburgh–Beacon Bridge – originally a single span in 1963, 2nd span added in 1980 * Thaddeus Kosciusko Bridge – commonly referred to as the "Twin Bridges", or just "The Twins" * Kosciuszko Bridge – twin cable-stayed spans, with their pylons mirrored on opposite sides of

Newtown Creek Newtown Creek, a long tributary of the East River, is an estuary that forms part of the border between the boroughs of Brooklyn and Queens, in New York City. River engineering#Channelization, Channelization made it one of the most heavily-use ...

* South Grand Island Bridge

References

Structural engineering Bridge design Duos {{Bridge-type-stub