Queen Elizabeth II Bridge

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Queen Elizabeth II Bridge
The Queen Elizabeth II Bridge at Dartford - geograph.org.uk - 1515684.jpg
The Queen Elizabeth II Bridge
Carries South-bound A282 4-lane road
Crosses River Thames
Design Cable-stayed bridge
Total length 812 m (2,664 ft)
Longest span 450 m (1,476 ft)
Vertical clearance 57.5 m (189 ft)
Opened 30 October 1991
Daily traffic 72,700 (2007/8 estimate[1])
Coordinates 51°27′52″N 0°15′31″E / 51.46444°N 0.25861°E / 51.46444; 0.25861

The Queen Elizabeth II Bridge is a 137 m (449 ft) high and 812 m (2,664 ft) long cable-stayed road bridge across the River Thames in south east England. It was opened in 1991 by Queen Elizabeth II.

The bridge is the southbound element of the A282 Dartford Crossing, joining the two ends of the M25 clockwise carriageway, a strategic congestion charged road crossing the half-mile wide river east of London. It was built alongside two earlier tunnels under the Thames, which now form the northbound element of the crossing.

Upon completion, the bridge was Europe's largest cable-supported bridge. As of 2010, by main span length, it is the second largest cable-stayed bridge in the United Kingdom behind the Second Severn Crossing (6 m longer and opened in 1996) and the 44th largest cable-stayed bridge in the world.

Locale[edit]

The bridge is the easternmost road bridge crossing the River Thames and is the only bridge over the river east of Greater London. At the time of opening it was only the second bridge on the River Thames east (downstream) of London Bridge constructed in over a thousand years. The historic reason for this is that bridges prohibited tall ships and other large ships from reaching the Pool of London, which has led to the building of numerous tunnels instead, until the construction of large bridges became feasible.

Specifications[edit]

The bridge as viewed from the approach to the tunnel.

The bridge's main span, the length of road deck between its two main towers (pylons), measures 450 metres (1,476 ft). This together with two 181 m outer spans either side gives the bridge an overall suspended road deck length of 812 metres (2,664 ft). The outer spans are also supported underneath by concrete pillars.

Connecting with the bridge's road deck joints are the approach roads, elevated on concrete viaducts. The northern elevated approach is 1,052 m (3,451 ft) long, while the southern elevated approach is 1,008 m (3,307 ft) long. The suspended bridge deck when combined together with the approach viaducts forms a total elevated stretch of road 2,872 m (9,423 ft) long.

The road deck of the bridge is supported by cables attached to 84 m (276 ft) metre high steel pylons rising above the road deck, standing on top of 53 m (174 ft) metre high concrete piers. These give the bridge an overall height of 137 m (449 ft).

The highest point of the road deck rises 65 m (213 ft) above the river, giving a clearance below to shipping of 57.5 m (189 ft) to accommodate all but the largest ocean-going cruise liners (for example the MS Freedom of the Seas is 63.7 m tall above the waterline).

Construction[edit]

The Queen Elizabeth II Bridge as viewed from Greenhithe, 2.5 km east of the bridge in Kent

The construction project of the bridge was an early example of a government Private Finance Initiative (PFI) project, whereby the bridge was funded by a private consortium in return for an operating concession. Authorised by a Parliamentary bill in 1988, construction began in August 1988 and was completed on 7 June 1991,[2] with the bridge being officially opened on 30 October 1991. The bridge has an expected life span of 120 years.

The bridge superstructure was designed by German civil engineer Hellmut Homberg.[3] The bridge was his last design as he died in July 1990. The bridge was built by Cleveland Bridge & Engineering Company, at the time part of Trafalgar House plc.[4] Construction of the bridge itself cost £120 million (£231 million as of 2014),[5] with another £30m for the approach road viaducts.[6]

Closure contingency[edit]

The height of the bridge means that it is sometimes closed due to high winds, accidents or in bad weather. Unlike other major bridges, the traffic disruption that this causes can be mitigated in part by the diversion of traffic through one of the Dartford tunnels which were in place before the bridge opened. Despite this, a closure still generates significant delays.

See also[edit]

References[edit]

  1. ^ The daily average for the Dartford Crossing as a whole was 145,466 vehicles as reported in [1] for the period April 2007 to March 2008. As the bridge is just one direction of the crossing, an estimate for the bridge alone is calculated by halving this figure, to give 72,733, rounded down to 72,700 for precision.
  2. ^ The History Channel: 9 June – This day in history
  3. ^ "History". The Dartford – Thurrock River Crossing. UK Highways Agency. 
  4. ^ Queen Elizabeth II Bridge on Structurae database
  5. ^ UK CPI inflation numbers based on data available from Gregory Clark (2013), "What Were the British Earnings and Prices Then? (New Series)" MeasuringWorth.
  6. ^ Bridge design stretched to the limits: Cable-stayed bridges are a type of suspended crossing. Spare but functional, they exploit a form of bridge engineering that is bringing down the cost of progressively longer crossings New Scientist magazine issue 1792, 26 October 1991, accessed 12 November 2008

External links[edit]