Short answers, pulled from the story.
A bridge is a structure designed to span an obstacle such as a river or railway, allowing vehicles, pedestrians, and other loads to pass across. Most bridges consist of a flat deck supported by beams, arches, or cables, resting on a foundation that transfers the weight to the subsoil without settling.
Bridges are primarily classified into six basic structural designs: arch, truss, cantilever, suspension, cable-stayed, and beam. Other forms include viaducts, trestles, causeways, movable bridges, and pontoon bridges.
A bridge span exceeded 2 kilometers for the first time in 2022 with the construction of the 1915 Canakkale Bridge. The maximum achievable span had increased steadily over time before reaching that milestone.
The Tacoma Narrows Bridge collapsed in 1940 in winds of 68 kilometers per hour, even though it was designed to withstand winds up to 206 kilometers per hour. Investigations found the designer failed to account for wind-induced flutter and resonant vibrations.
The George Washington Bridge in New York is the world's busiest bridge, carrying over 100 million vehicles annually. It is a double-deck bridge with 14 motor vehicle lanes, eight above and six below.
Bridge designers can choose from wood, brick, rope, stone, iron, steel, and concrete. Steel is one of the most common modern materials because it is strong in both compression and tension, while concrete is widely used for beam and box girder structures when reinforced with embedded steel.
Underwater foundations were built using caissons, which are large watertight structures open on the bottom and sunk to the riverbed so workers could prepare the ground for footings. Thirteen workers died of decompression sickness while building the Eads Bridge, completed in 1874, because early builders did not understand decompression.