Gateway Arch

Gateway Arch
U.S. National Register of Historic Places
U.S. National Historic Landmark
The Gateway Arch in April 2010.
Location	Missouri
Area	62.165 acres
Built	constructed 1963-1965 design created 1947
Architect	Eero Saarinen
NRHP reference No.	87001423
Significant dates
Added to NRHP	May 28, 1987
Designated NHL	May 28, 1987

The Gateway Arch, also known as the Gateway to the West, is an integral part of the Jefferson National Expansion Memorial and the iconic image of St. Louis, Missouri.It was made to honor the westward expansion.It was designed by Finnish-American architect Eero Saarinen and structural engineer Hannskarl Bandel in 1947. It is 630 feet (192 metres) wide at its base and stands 630 feet (192 metres) tall, making it the tallest monument in the United States. Construction started on February 12, 1963, and ended on October 28, 1965. The monument opened to the public on July 10, 1967.

Physical description

The cross-sections of its legs are equilateral triangles, narrowing from 54 feet (16 metres) per side at the base to 17 feet (5.2 metres) at the top. Each wall consists of a stainless steel skin covering a sandwich of two carbon steel walls with reinforced concrete in the middle from ground level to 300 feet (91 metres), with carbon steel and rebar from 300 feet (91 metres) to the peak. The Arch is hollow and contains a unique tram system that brings visitors to an observation deck at the top. The interior also contains two stairwells of 1,076 steps each for use in emergencies.

The base of each leg at ground level had an engineering tolerance of one-64th of an inch (0.40 mm) or the two legs would not meet at the top.

During construction, both legs were built simultaneously. When the time came to connect the legs at the apex, thermal expansion of the sunward-facing south leg prevented it from aligning precisely with the north leg. The St. Louis Fire Department sprayed the south leg with water from firehoses, cooling it until it aligned with the north leg.

Tram

The tram is an egg-shaped "elevator". It is operated by the quasi-governmental Bi-State Development Agency under an agreement with the NPS.

From the visitor center, one may move to either base (one on the north end and the other on the south end) of the Arch and enter the tramway much as one would enter an ordinary elevator, through narrow double doors. The north queue area includes displays that interpret the design and construction of the Gateway Arch; the south queue area includes displays about the St. Louis riverfront during the mid-19th century.

Passing through the doors, passengers in groups of five enter an egg-shaped compartment containing five seats and a flat floor. Because of the car shape, the compartments have sloped ceilings low enough to force taller riders to lean forward while seated (for this reason it's recommended that the tallest of the five passengers in the car sit in the center seat facing the door). Eight compartments are linked to form a train, meaning that both trains have a capacity of 40, and that 80 people can be transported at one time. These compartments rotate 5 degrees from time to time, keeping them upright while the entire train follows curved tracks up one leg of the arch. The trip to the top takes four minutes, and the trip down takes three minutes. The car doors have narrow windows, allowing passengers to see the interior stairways and structure of the Arch during the trip.

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  Interior of the tram capsule in the Gateway Arch.
• 
  Entrance doors as viewed from inside the tram capsule.

Observation area

Near the top of the arch, the rider exits the compartment and climbs a slight grade to enter the arched observation area. Thirty-two windows (16 per side) measuring 7 by 27 inches (180 by 690 millimetres) allow views across the Mississippi River and southern Illinois with its prominent Mississippian culture mounds to the east at Cahokia Mounds, and the City of Saint Louis and St. Louis County to the west beyond the city. On a clear day, one can see up to 30 miles (48 km).

• 
  Observation area on top of the arch
• 
  Gateway Arch view from Observation Area
• 
  Southern entrance to the subterranean visitor center.

Mathematics of the Arch

Curvature detail with the windows of the observation deck located around the apex of the arch.

The geometric form of the Arch was set by mathematical equations provided to Saarinen by Dr. Hannskarl Bandel. Bruce Detmers and other architects expressed the geometric form in blueprints with this equation:

$y=A\left(\cosh {\frac {Cx}{L}}-1\right)\quad \Leftrightarrow \quad x={\frac {L}{C}}\cosh ^{-1}\left(1+{\frac {y}{A}}\right)$,

with the constants

$A={\frac {f_{c}}{Q_{b}/Q_{t}-1}}=68.7672$

$C=\cosh ^{-1}{\frac {Q_{b}}{Q_{t}}}=3.0022$

where f_c = 625.0925 ft (191 m) is the maximum height of centroid, Q_b = 1,262.6651 sq ft (117 m²) is the maximum cross sectional area of arch at base, Q_t= 125.1406 sq ft (12 m²) is the minimum cross sectional area of arch at top, and L = 299.2239 ft (91 m) is the half width of centroid at the base.

This hyperbolic cosine function describes the shape of a catenary. A chain that supports only its own weight forms a catenary; in this configuration, the chain is strictly in tension. An inverted catenary arch that supports only its own weight is strictly in compression, with no shear. The gateway arch itself is not a catenary, but a more general curve called a flattened catenary of the form y=Acosh(Bx); a catenary is the special case when AB=1. While a catenary is the ideal shape for an arch of constant thickness, the gateway arch does not have constant thickness as it is narrower near the top.

Security

In 2010, Congress required the NPS to establish a counterterrorism program at the park, so the service bought magnetometers and x-ray equipment to screen visitors at the visitors' center entrances and installed 25 CCTV cameras throughout the grounds of the memorial. There are barriers around the grounds to keep vehicles out.

Notable events

A time capsule containing the signatures of 762,000 St. Louis area students was welded into the keystone before the final piece was set in place.

Eleven light aircraft have been flown through the arch, the first on June 22, 1966, less than a year after construction was completed.

In 1980, Kenneth Swyers tried to parachute onto the Gateway Arch. He had planned to subsequently jump off and land on the ground. Instead, he slid all the way down one leg to his death. The pilot, Richard Skurat, had his pilot certificate suspended for 90 days.

In 1984, David Adcock of Houston, Texas, began to scale the arch using suction cups on his hands and feet, but he was talked out of continuing after having climbed only 20 feet (6.1 m). The next day, he scaled the nearby 21-story Equitable Building in downtown St. Louis.

The Arch was declared a National Historic Landmark in 1987.

On September 14, 1992, it was rumored that John C. Vincent of New Orleans scaled the outside of the Arch with suction cups during the night, and performed a BASE jump from the top with a parachute at 7 a.m. No evidence surfaced to support his claim, and it was speculated by Park Rangers that Vincent was lowered from a helicopter onto the top of the Arch, from which he parachuted. He was jailed three months for the stunt.

On July 21, 2007, about 200 people were trapped in the trams or at the top of the Arch after an electrical problem occurred with the tram system. All returned safely to the ground via the stairs or by the trams after power was restored. A second electrical problem caused one tram to be taken out of service the following day.

Cultural references

Film

• In the film The Black Hole, the arch is destroyed by a black hole.
• In the film Category 6: Day of Destruction, the arch is destroyed by a tornado.
• In the film Supernova, the arch is destroyed when meteors coming from a supernova rip it in two.
• In the opening credits of the HBO miniseries Angels in America, the arch is shown as part of a flight sequence over several American landmarks.

Other

• The Gateway Arch has been a featured Santa Cam location since the 2002 NORAD Tracks Santa tracking season.
• The Gateway Arch has been featured in the book Percy Jackson & the Olympians: The Lightning Thief.

See also

• Gateway Geyser
• Jefferson National Expansion Memorial

External links

• Official Site
• Panoramic West view from observation area
• Lines of Authority Time Magazine retrospective article
• Photographs of the St. Louis Gateway Arch
• "Gateway Arch Construction photographs". University of Missouri–St. Louis.
• How The Arch Got Its Shape