The Burr Arch Truss — or simply Burr Truss or Burr Arch — is a combination of an arch and a multiple kingpost truss design. It was invented in 1804 by Theodore Burr

Theodore Burr

Theodore Burr was an inventor from Torringford, Connecticut, who was credited with the Burr Arch Truss bridge design and was cousin of vice president Aaron Burr. Theodore Burr came to Oxford, New York in 1792. By 1794, he had built a grist mill , and a dam to power the mill...

, patented on April 3, 1817, and used in bridge

Bridge

A bridge is a structure built to span physical obstacles such as a body of water, valley, or road, for the purpose of providing passage over the obstacle...

s, usually covered bridge

Covered bridge

A covered bridge is a bridge with enclosed sides and a roof, often accommodating only a single lane of traffic. Most covered bridges are wooden; some newer ones are concrete or metal with glass sides...

s.

Design

The design principle behind the Burr arch truss is that the arch should be capable of bearing the entire load on the bridge while the truss keeps the bridge rigid. Even though the kingpost truss alone is capable of bearing a load, this was done because it is impossible to evenly balance a dynamic load crossing the bridge between the two parts. The opposite view is also held, based on computer models, that the truss performs the majority of the load bearing and the arch provides the stability. Either way, the combination of the arch and the truss provides a more stable bridge capable of supporting greater weight than either the arch or truss alone.

Gallery

Indiana has a large collection of Burr Truss bridges. Of its 92 extant bridges, 53 are Burr Trusses, many of which reside in Parke County

Parke County, Indiana

Parke County is a county in the western part of the U.S. state of Indiana. It was formed in 1821 out of a portion of Vigo County. The county seat is Rockville....

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