The Gateway Arch was designed in 1947. Construction started in early 1963 and it opened to the public in October 1965. It was built to commemorate westward expansion by early American settlers and is a representation of the "Gateway to the West" status which St Louis occupied after Jefferson bought a huge portion of North America from Napoleon. The monument is in fact part of a bigger Jefferson memorial.
At its highest point it stands 630 feet.
Its appearence seems to change with the sun's march east to west.
The arms of the arch were built simultaneously and when the time came to connect them, thermal expansion of the southern, sun facing section prevented the two arms from aligning precisely.
Imagine that sphincter tightening moment for the head foreman!
The answer to the problem was decidedly low tech:
The St Louis Fire Department sprayed the South leg with hoses until it cooled enough to align with the northern leg.
The arch itself is hollow allowing visitors to travel up inside the twisting shell to observation decks at its apex.
More on that later.
It's a marvel to look at and I think much of its beauty stems from its twisting slender legs which seem to defy laws of physics.
How does it stay upright and whole?
Well, according to the math...........
where fc = 625.0925 ft (191 m) is the maximum height of centroid, Qb = 1,262.6651 sq ft (117 m2) is the maximum cross sectional area of arch at base, Qt= 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.
I'm glad thats settled.
Eleven aircraft have flown through the arch and a couple of wing nuts have tried to use it for a number of stunts.
- In 1980 Kenneth Swyers tried to parachute onto the top of the arch, planning to then jump off again and land safely in thesurrounding park. Instead he slid all the way down the northern leg (cartoon style) and landing on his head met a messy end.
- On September 14 1992, John Vincent did a base jump from the top. He claimed he'd scaled the structure using suction cups, but was unable to furnish any evidence in support. Cops speculated he'd been lowered by helicopter though no one saw or heard anything. Vincent spent 3 months in the slammer.
To get to the top you travel in an "egg" capsule (5 to a pod).
Being tall, I spent the 4 minute ascent hunched over looking at the knees of the muttering claustrophobic woman seated to my left. The egg rotates 5 degrees during the climb in order to remain upright as the pod travels the curved spine of the leg.
On July 21st, 200 people were trapped in the trams at the top of the arch after an electrical failure.
All got back to the ground safely though nerves were undoubtedly frayed.
Viewed from the ground the apex looks impossibly thin. The observation deck is actually surprisingly spacious.