Chain Bridge (Washington, D.C.)
Encyclopedia
The Chain Bridge is a viaduct which crosses the Potomac River
Potomac River
The Potomac River flows into the Chesapeake Bay, located along the mid-Atlantic coast of the United States. The river is approximately long, with a drainage area of about 14,700 square miles...

 at Little Falls in Washington, D.C.
Washington, D.C.
Washington, D.C., formally the District of Columbia and commonly referred to as Washington, "the District", or simply D.C., is the capital of the United States. On July 16, 1790, the United States Congress approved the creation of a permanent national capital as permitted by the U.S. Constitution....

  It carries close to 22,000 cars a day. It connects Washington with affluent sections of Arlington and Fairfax counties in Virginia. On the Washington side, the bridge connects with Canal Road. Turns onto the Clara Barton Parkway from the Chain Bridge are prohibited, but the reverse is permitted. On the Virginia side, the bridge connects with State Route 123 (Chain Bridge Road), which provides access to the George Washington Memorial Parkway.

The Chain Bridge has three lanes (of which the center is reversible
Reversible lane
A reversible lane , called a counterflow lane or contraflow lane in transport engineering nomenclature, is a lane in which traffic may travel in either direction, depending on certain conditions...

) and can be safely accessed by pedestrians and cyclists. The pedestrian sidewalk provides access to the Chesapeake and Ohio Canal
Chesapeake and Ohio Canal
The Chesapeake and Ohio Canal, abbreviated as the C&O Canal, and occasionally referred to as the "Grand Old Ditch," operated from 1831 until 1924 parallel to the Potomac River in Maryland from Cumberland, Maryland to Washington, D.C. The total length of the canal is about . The elevation change of...

 towpath
Towpath
A towpath is a road or trail on the bank of a river, canal, or other inland waterway. The purpose of a towpath is to allow a land vehicle, beasts of burden, or a team of human pullers to tow a boat, often a barge...

 via a ramp.

History

The first bridge at the location was opened on July 3, 1797. It was a wooden covered bridge, and rotted and collapsed in 1804. The second bridge, of similar type, burned six months after it was built.

The third bridge was built four years later in 1808, and is where the bridge received its name. It was a chain suspension bridge, using 1¼ inch bars. It was designed by Judge James E. Finley, and was 136 feet long by 15 feet wide. It was destroyed by flood in 1810 or 1812. The fourth bridge was also a chain suspension bridge, and though damaged by floods in 1815, it lasted until 1840.

The fifth bridge was built in 1840, and made of chain and wood. This span collapsed in 1852 and was replaced by a crossbeam truss
Truss
In architecture and structural engineering, a truss is a structure comprising one or more triangular units constructed with straight members whose ends are connected at joints referred to as nodes. External forces and reactions to those forces are considered to act only at the nodes and result in...

 structure that resembled a long garden arbor or pergola
Pergola
A pergola, arbor or arbour is a garden feature forming a shaded walkway, passageway or sitting area of vertical posts or pillars that usually support cross-beams and a sturdy open lattice, often upon which woody vines are trained...

, but retained its historical name. During the American Civil War
American Civil War
The American Civil War was a civil war fought in the United States of America. In response to the election of Abraham Lincoln as President of the United States, 11 southern slave states declared their secession from the United States and formed the Confederate States of America ; the other 25...

, the Chain Bridge was a popular place for the Union Army to access the countryside encampments from Fairfax County
Fairfax County, Virginia
Fairfax County is a county in Virginia, in the United States. Per the 2010 Census, the population of the county is 1,081,726, making it the most populous jurisdiction in the Commonwealth of Virginia, with 13.5% of Virginia's population...

.

The bridge is the site of the first Union Army Balloon Corps
Union Army Balloon Corps
The Union Army Balloon Corps was a branch of the Union Army during the American Civil War, established by presidential appointee Thaddeus S. C. Lowe...

 balloon crossing, which took place overnight on October 12, 1861, conducted by Professor Thaddeus S. C. Lowe
Thaddeus S. C. Lowe
Thaddeus Sobieski Coulincourt Lowe , also known as Professor T. S. C. Lowe, was an American Civil War aeronaut, scientist and inventor, mostly self-educated in the fields of chemistry, meteorology, and aeronautics, and the father of military aerial reconnaissance in the United States...

 and a band of handlers who had to precariously traverse the outsides of the fully trellised bridge. In a nine hour ordeal, the balloon Eagle was fully inflated in Washington and walked out to the battlefield at Lewinsville
Lewinsville, Virginia
Lewinsville is an unincorporated community in Fairfax County, Virginia, USA. Traditionally, the center of Lewinsville has been located at the crossroads of Lewinsville and Chain Bridge Roads. Together with Langley, Lewinsville forms the census-designated place of McLean....

, Virginia.

The truss bridge was swept away in an 1870 flood, and a lightweight iron truss replacement was erected in 1872-1874. Traffic restrictions were placed on the bridge in the 1920s, and it was fully closed following the record flood of 1936. The eighth and present version of the bridge is a continuous steel girder
Girder
A girder is a support beam used in construction. Girders often have an I-beam cross section for strength, but may also have a box shape, Z shape or other forms. Girder is the term used to denote the main horizontal support of a structure which supports smaller beams...

 structure, completed in 1939 on piers dating from the 1870s.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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