The Rogue River Bridge was the most advanced concrete bridge in America when it was built. Distinguished bridge engineer Conde McCullough employed the techniques of Frenchman Eugene Freyssinet to create thin, graceful concrete arches for this seven-span structure.
Pre-compression of the concrete arch was achieved and, as a result of its success, pre-stressing became one of the hallmarks of American bridge building techniques.
The workforce consisted of less than 100 men, yet they finished construction in just 94 days. Such speed was possible due to the elimination of scaffolding. Instead, iron rods were used to support construction of the trusses between the towers, and workers moved back and forth across the rods. A dangerous venture, yet no workers were seriously injured.
In 1866, the Covington and Cincinnati Suspension Bridge was the largest suspension bridge in the world. Also called the Ohio Bridge, it was officially renamed the John A. Roebling Bridge in 1983. It was the first permanent bridge over the Ohio River and the only public project in America financed by private investors during the Civil War.
Renowned bridge designer John A. Roebling proposed the structure in 1846; but building the bridge would become a 20-year saga, with heated lobbying both for and against the crossing.
The Detroit-Windsor Tunnel is a 5,160-foot structure that carries traffic under the Detroit River between Detroit, Michigan and Ontario, Canada. Privately financed, built, and owned, it was completed in 26 months, 10 months ahead of schedule.
The Carrollton Viaduct over Gwynn's Falls was the first masonry railroad viaduct constructed in the United States. This structure proved the feasibility of using a viaduct to transport railway vehicles across wide and deep valleys.
This was a pioneering venture in mainline railroad electrification. It established single-phase alternating current as a technical and economical alternative to direct current. This concept exerted considerable influence over subsequent systems both in the United States and abroad. The major components of the system were developed by the engineering staffs of the New York, New Haven & Hartford Railroad and the Westinghouse Electric and Manufacturing Company of East Pittsburgh, Pennsylvania.
The 1.6-mile Holland Tunnel was the first underwater vehicular crossing of the Hudson River and the first tunnel specifically designed for automobiles and trucks. It dramatically reduced the time required to traverse the Hudson River, a trip previously possible only by ferry.
A major difficulty when tunneling beneath a river is to keep water and mud from inundating the workers and equipment in the tunnel. Builders of the Holland Tunnel used a shield that enveloped the work site as the excavation progressed; this also avoided obstruction of shipping traffic during construction.
During the 1930's, research into advanced ballistic measurement techniques began at Aberdeen Proving Ground—the world's first large-scale, fully-instrumented ballistic range producing data on the aerodynamic characteristics of missiles in free flight.
