Bridges

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.

This bridge is recognized as the first iron bridge in the world. This rural region of England was an important industrial area thanks to coal deposits near the surface. In 1776 the nearest bridge that enabled people and goods to pass over the River Severn was two miles away at Buildwas. There was a ferry crossing, but the trip was difficult and dangerous especially in winter. In 1776, an Act to build a bridge to remedy this situation received Royal Assent.

"Some of New Hampshire's most aesthetically pleasing yet least appreciated structures are stone arch bridges."

"The majestic Forth Bridge ... symbolises the tremendous achievements of Victorian engineers and the immense strides made in the technique of bridge design and construction since the dawn of the Railway Age..."
 - Derrick Bennett, Bridges: Great Buildings of the World

"Fink's truss design was one of a number of early patented solutions to [the problem of how] to carry a massive, moving weight (a train) over long spans (to avoid the expense of building piers and obstructing waterways) on easily erected bridges (often in rough terrain) with good long-term economy..." 
 - Kent Farnow Smith, "America's Oldest Functioning Iron-Truss Bridge," 1978

Designed by William A. Truesdell, a railroad engineer, the Seventh Street Improvement Arches celebrates the engineering application of mathematics to improve living conditions.