Duck Creek Aqueduct is a rare surviving example of a covered timber aqueduct. It was one of several similar structures on the Whitewater Canal, which operated between the Whitewater Valley and the Ohio River from 1839 to 1865. After being displaced by the railroad, the canal supplied hydraulic power for the industrial districts at Metamora and Brookville.
Doe River Bridge is a fine example of a timber Howe truss, one of the most widely-used timber bridge designs. Built in 1884, this structure played an integral role in the development of the City of Elizabethton, Tennessee, and it is a rare example of a covered bridge that survives in an urban setting.
The original contract specified the unusual hip roof design, which resembles covered bridges in central Europe. The structure is very well-maintained and still carries automobile traffic. The bridge was restored in 2003.
Bunker Hill Bridge is the only surviving Haupt truss bridge in the U.S. and one of only two surviving covered bridges in North Carolina. Patented in 1839, the Haupt truss featured diagonal braces spanning multiple panels, which was an attempt to eliminate the cross-strain found in lattice truss bridges. Although it was almost immediately eclipsed by the Howe truss and never reached the mainstream of covered bridge building, the Haupt truss is of interest for its association with Gen.
The Ashuelot Covered Bridge is located at the center of Ashuelot, NH. It is a Town lattice truss bridge, spanning the Ashuelot River in a roughly north-south orientation. It consists of two spans with a total length of 178 feet (54 m). The total width of the bridge is 29 feet (8.8 m), and has a central roadway and sidewalks (measuring 3'10" in width) on each side. The bridge rests on stone abutments and a central pier. The abutments have been reinforced with concrete since the bridge was built, and the central pier has been protected by a metal breakwater.
Ackley Bridge is an excellent example of a multiple kingpost truss and a noteworthy early example of covered bridge preservation efforts in the United States. Built in 1832 by Joshua Ackley (b.1805) and Daniel Clouse (b.1812), Ackley Bridge originally spanned Enslow’s Branch of Wheeling Creek between Greene County and Washington County in Pennsylvania, where it carried traffic for over a century.
In the 1940s and 1950s, New Orleans experienced growth. Unfortunately, access from the north to the City continued to be limited by Lake Pontchartrain. Driving around the Lake was a time consuming effort. During this time period, a renewed interest developed to provide a direct connection across the center of the Lake to the north shore. As a result, the Greater New Orleans Expressway Commission was formed to build the Lake Pontchartrain Causeway Bridge. The original bridge (southbound) was opened on August 30, 1956.
Taken together, the 1940 and 1950 Tacoma Narrows bridges mark a significant turning point in the design of long-span suspension bridges. The original 1940 structure was designed with one of the shallowest and narrowest stiffening elements of any long-span suspension bridge yet built. The structure failed dramatically in a rather moderate 42 mph windstorm on 7 November 1940, only four months after opening for traffic.
In 1915, a tropical storm dropped nearly 11 inches of rain on St. Louis in just 17 hours, causing a devastating flood. Claiming 11 lives and the homes of 1,025 families, the flood focused public and government attention onto the problems of the river.
The Chamberlain is the only surviving bridge of the original five. The others were replaced as the river rose due to flood control dams put in place over time.
The 1.5 mile Lacey V. Murrow Bridge was the largest floating structure in the world and the first to be built of reinforced concrete when completed in 1940. The bridge consisted of typically 300-foot long pontoons floated to site and rigidly connected to form a continuous structure and incorporated a unique floating concrete draw-span to allow for passage of marine traffic. The original floating structure, constructed by Pontoon Bridge Builders, was accidentally sunk in 1990 during a major renovation effort and was replaced by 1993.