A truss bridge is a bridge whose load-bearing superstructure is composed of a truss, a structure of connected elements, usually forming triangular units. The connected elements, typically straight, may be stressed from tension, compression, or sometimes both in response to dynamic loads. There are several types of truss bridges, including some with simple designs that were among the first bridges designed in the 19th and early 20th centuries. A truss bridge is economical to construct primarily because it uses materials efficiently.
The Three Sisters are three similar self-anchored suspension bridges spanning the Allegheny River in downtown Pittsburgh, Pennsylvania at 6th, 7th, and 9th streets, generally running north–south. The bridges have been given formal names to honor important Pittsburgh residents:
The Roberto Clemente Bridge, also known as the Sixth Street Bridge, spans the Allegheny River in downtown Pittsburgh, Pennsylvania, United States.
The Coraopolis Bridge[1] is a girder bridge over the back channel of the Ohio River connecting Grand Avenue on Neville Island to Ferree Street in Coraopolis, Pennsylvania. It opened in 1995 to replace a structure of historic significance. The original Pratt/Bowstring/Pennsylvania[2] through truss spans, designed by Theodore Cooper, were formerly the (third) Sixth Street Bridge, spanning the Allegheny River, in downtown Pittsburgh, and were built in 1892 by the Union Bridge Company. They were floated downstream by the Foundation Company in 1927 rather than being demolished when the bridge was removed to enable construction of the present (fourth) Three Sisters (Pittsburgh) Sixth Street Self-anchored suspension bridge. However, by the late 1980s, the old bridge could no longer support traffic volumes and was replaced by a newer structure.
The Homestead Grays Bridge, also known as the (Homestead) High Level Bridge, was built in 1936 and spans the Monongahela River between Homestead Borough and the southernmost tip of Pittsburgh's Squirrel Hill neighborhood. It is notable as the first bridge to incorporate the Wichert Truss, which uses a quadrilateral shape over each support, into its design. This made the truss statically determinate, so that forces in the structural members could be calculated. There are very few surviving Wichert Truss bridges, including one other example in Pittsburgh, the Charles Anderson Memorial Bridge.
The Glenwood B&O Railroad Bridge is a truss bridge in Pittsburgh, Pennsylvania, which carries Allegheny Valley Railroad's W&P Subdivision over the Monongahela River.
The Fort Wayne Railroad Bridge, listed as the Pennsylvania Railroad Bridge on the National Register of Historic Places, is a double-deck steel truss railroad bridge spanning the Allegheny River in Pittsburgh, Pennsylvania.
The West End Bridge is a steel tied-arch bridge over the Ohio River in Pittsburgh, Pennsylvania, approximately 1 mile (1.6 km) below the confluence of the Allegheny and Monongahela Rivers. It connects the West End to the Chateau neighborhood on the North Side of Pittsburgh.
The McKees Rocks Bridge is a steel trussed through arch bridge which carries the Blue Belt, Pittsburgh's innermost beltline, across the Ohio River at Brighton Heights and McKees Rocks, Pennsylvania, connecting Pennsylvania Route 65 with Pennsylvania Route 51, west of the city.
The Sorlie Memorial Bridge, also known as the Red River Bridge, was constructed in 1929 by the Minneapolis Bridge Company to connect the cities of Grand Forks, North Dakota and East Grand Forks, Minnesota. It was placed on the National Register of Historic Places in 1999.
The 33rd Street Railroad Bridge is a truss bridge that carries the Allegheny Valley Railroad on the P&W Subdivision over the Allegheny River that connects downtown Pittsburgh, Pennsylvania to Herrs Island, Pittsburgh, United States.
The Allegheny River Turnpike Bridge carries Interstate 76 over the Allegheny River. The structure features a pair of twin 2,350’ cast-in-place concrete segmental bridges. This is the first of its type in Pennsylvania. It was constructed between 2007 and 2010 and is the second bridge to stand on this site. The original truss bridge was built between 1949 and 1951 by the engineering firm Modjeski & Masters; the crossing predates the Interstate System by several years.
The Herr's Island Railroad Bridge, also known as the West Penn Railroad Bridge, is a truss bridge across the Allegheny River in the United States between the Pittsburgh neighborhoods of Troy Hill and Herrs Island.
The 30th Street Bridge is a girder bridge that carries vehicular traffic across the Allegheny River between the Pittsburgh neighborhoods of Troy Hill and Herrs Island. This is the fourth bridge that has stood on this site. A wooden 19th Century bridge was washed away during an 1882 flood. This was replaced by an arch bridge that spanned the entire width of the Allegheny River; after a 1921 fire destroyed the span across the main channel, the 31st Street Bridge was constructed as a replacement, and this bridge was again relegated to taking traffic to Herrs Island. A 1939 truss bridge then stood on this site, and it was replaced by the current structure as part of the redevelopment of the island to feature condominiums and a business park instead of warehouses and stockyards.
The William Raymond Prom Memorial Bridge, commonly known as the 31st Street Bridge, is an arch bridge that carries vehicular traffic across the Allegheny River between the Pittsburgh neighborhoods of Troy Hill and the Strip District. The bridge passes over but does not serve Washington's Landing, which is connected to the mainland by the 30th Street Bridge. Sidewalks along the bridge feature viewing platforms.
The Senator Robert D. Fleming Bridge, commonly known as the 62nd Street Bridge, is a truss bridge that carries Pennsylvania Route 8 across the Allegheny River between the Pittsburgh neighborhoods of Morningside and Lawrenceville and Sharpsburg, Pennsylvania.
The Highland Park Bridge is a truss bridge that carries vehicular traffic across the Allegheny River between the Pittsburgh neighborhood of Highland Park and the suburb of Aspinwall.
The Brilliant Branch Railroad Bridge is a truss bridge that carries Allegheny Valley Railroad's Brilliant Branch across the Allegheny River between the Pittsburgh neighborhood of Highland Park and the borough of Aspinwall, Pennsylvania.
Bridge 15, also known locally as the River Bridge, spans the White River in Sharon, Vermont. Built in 1928, this multi-span Parker truss bridge is one of a shrinking number of White River crossings of this type. It was listed on the National Register of Historic Places in 2008.
The Lyme–East Thetford Bridge is a historic bridge over the Connecticut River between Lyme, New Hampshire, and East Thetford, Vermont. From the New Hampshire side it carries East Thetford Road, which becomes Vermont Route 113 as it enters Vermont. A Parker truss bridge completed in 1937, it is 471 feet (144 m) long. The bridge was added to the National Register of Historic Places in 2020.
PA 368, pedestrians
