Little Bits of History

Wobbly Bridge

Posted in History by patriciahysell on June 10, 2015
London Millennium Footbridge as seen from Saint Paul's Cathedral

London Millennium Footbridge as seen from Saint Paul’s Cathedral*

June 10, 2000: The Millennium Bridge, London opens. Officially called the London Millennium Footbridge, it was a uniquely designed steel suspension bridge for pedestrians crossing the River Thames. It is unofficially called the Wobbly Bridge. The south side of the bridge is located near the Globe Theatre, the Bankside Gallery, and Tate Modern. The north side is next to the City of London School below St. Paul’s Cathedral. The bridge was built so that a clear view of the cathedral’s façade is seen as one crosses the river and it is framed by the bridge supports.

In 1996, a competition was held by the Southwark council and RIBA Competitions. The winners were Arup, Foster and Partners and Sir Anthony Caro with their novel plan “blade of light”. There were height restrictions to help improve the view so the supporting cables were below the deck level. The bridge was designed with two river piers and has three main sections, each a different length: 266 feet, 472 feet, and 354 feet from North to South. The total length of the structure is 1,066 feet and the aluminum deck is 13 feet wide. There are eight suspension cables pulled to a force of 2,000 tons against the piers set in each of the river’s banks. It was designed to support a working load of 5,000 people.

Usually an Act of Parliament is required to build a bridge across the River but on this occasion (the first in over 100 years), Port of London Authority granted a license instead. Construction began in 1998 with the main work beginning in April 1999 with Monberg & Thorsen and Sir Robert McAlpine building the bridge at a cost of £18.2 million (£2.2 million over budget) and opened on this date (two months late). The cost of the bridge was paid for by the Millennium Commission and the London Bridge Trust. For the opening day’s ceremonies, volunteer for Save the Children walked across the bridge. As they did so, they noticed an eerie swaying motion. They unconsciously began walking in step which only increased the phenomenon.

After they made it safely to the other side, there was only limited traffic permitted on the bridge. Two days later, the bridge was closed. The walkers’ natural movements caused a small sideways oscillation in the bridge and as they continued to walk, the movement was amplified. There were 90,000 people who walked across the bridge on opening day, with 2,000 at a time as the highest number. It took two years of modifications to completely get the “wobble” out of Wobbly Bridge. These lateral vibrations are unusual, but not unique as other bridges have been known to experience the same problem. The bridge was retrofitted with 37 fluid-viscous dampers for horizontal control and 52 tuned mass dampers for vertical control. The bridge reopened in February 2002 after spending another £5 million for repairs. While the wobble is now completely gone, the name sticks.

There is nothing in machinery, there is nothing in embankments and railways and iron bridges and engineering devices to oblige them to be ugly. Ugliness is the measure of imperfection. – H. G. Wells

A pier is a disappointed bridge. – Julian Barnes

Someday when peace has returned to this odd world I want to come to London again and stand on a certain balcony on a moonlit night and look down upon the peaceful silver curve of the Thames with its dark bridges. – Ernie Pyle

It has always seemed to me that the most difficult part of building a bridge would be the start. – Robert Benchley

Also on this day: Friends of Bill – In 1935, Alcoholics Anonymous was formed.
US Naval Academy – In 1854, the first class graduated from USNA.
Oxford v. Cambridge –  In 1829, the first Boat Race between the two schools took place.
Teenager Sees Reds – In 1944, Joe Nuxhall went pro.
Equal Pay – In 1960, the Equal Pay Act was signed into law.

* “London Millennium Bridge from Saint Paul’s” by Jan Kameníček – Own work. Licensed under CC BY-SA 3.0 via Wikimedia Commons – http://commons.wikimedia.org/wiki/File:London_Millennium_Bridge_from_Saint_Paul%27s.jpg#/media/File:London_Millennium_Bridge_from_Saint_Paul%27s.jpg

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