Gateway Arch

The Seven Forgotten Modern Wonders of the World

Located on the banks of the Mississippi River in St. Louis, Missouri, the 630-foot tall stainless steel, the Gateway Arch rises above the city skyline. It is a part of the Jefferson National Expansion Memorial - which also contains the Museum of Westward Expansion, and the St. Louis' Old Courthouse. It is based on architect Eero Saarinen's design, who was the winner of the competition held a nation wide in 1947-1948.

The construction of the arch began on February 12, 1963, was finished on October 28, 1965 and was opened to the public on July 24, 1967 (after one of the trams was completed). It cost about $ 13 million to build. The two bases are equilateral triangles with sides 54 ft long. At the top of the arch, the triangle is only 17 feet long on each side. Visitors enter the arch from an underground visitor's center and can travel to the observation deck at the top in a 40-passenger tram that runs inside the arch.

The St. Louis Gateway Arch, standing at a height of 630 ft, is in the form of an inverted catenary, which is a very stable structure that is often used in bridges, domes, and arches. A catenary is the shape that a chain or necklace forms when held by the two ends. The Dutch mathematician Christiaan Huygens named this curve from the Latin word catenarius, which means 'related to a chain'.

The arch has 60-foot deep foundations and weighs 43,000 tons. The arch is very stable and was built to withstand high winds and earthquakes (the Gateway Arch sways about one inch in a 20 mph wind and is designed to sway up to 18 inches in 150 mile per hour winds). Its exterior is composed of stainless steel. Trams, designed by Dick Bowser (who never went to college), are used to travel through the triangular shafts.

The first attempts in designing an appropriate system were based on several schemes, beginning with elevators. To get 3,500 people to the top of the Arch, which is the equivalent of a 63-story building, during an 8 hour day would require more than an ordinary elevator. Because of the triangular shape and the different slopes in the Arch, a standard elevator could only go up about 300 ft. Above that level, a small elevator at a steeper angle would be required. Standard elevators were therefore determined to be impractical.

The next solutions to be considered were escalators, the Ferris wheel and many others, but, there remained several inconsistencies in all of them. Finally, Dick Bowser put forward his proposal for the tramway, which made traveling through the Gateway Arch both convenient and possible. However, the interior of the Arch also contains two emergency stairwells in the event of a need to evacuate the Gateway Arch or if a problem develops with the tram system.