Tinsley Viaduct

Tinsley Viaduct
Tinsley Viaduct as seen from Meadowhall, with the two cooling towers of the former Blackburn Meadows power station prior to their demolition in 2008.
Coordinates
Carries	M1 A631
Crosses	River Don Sheffield Canal Midland Main Line South Yorkshire Railway
Locale	Tinsley/Wincobank
Maintained by	Highways Agency
Characteristics
Design	twin deck box girder bridge
Total length	1,033 m (3,389 ft)
Width	6 lanes
Height	20 m (66 ft) (to upper level)
Longest span	50 m (160 ft) (20 spans)
Clearance above	10 m (33 ft) (on the A631)
Clearance below	10 m (33 ft)
History
Construction begin	Spring 1965
Construction end	1968
Opened	25 March 1968
Statistics
Daily traffic	100,000 vehicles/day
Tinsley Viaduct shown within South Yorkshire grid reference SK394913

Tinsley Viaduct is a two-tier road bridge in Sheffield, England; the first of its kind in the UK. It carries the M1 and the A631 1033 metres over the Don Valley, from Tinsley to Wincobank, also crossing the Sheffield Canal, the Midland Main Line and the former South Yorkshire Railway line from Tinsley Junction to Rotherham Central. The Supertram route to Meadowhall runs below part of the viaduct on the trackbed of the South Yorkshire Railway line to Barnsley.

History

Tinsley Viaduct lower deck.

The viaduct was opened in March 1968 and cost £6 million to build. The structure is unusual in that it is built as steel box girders, at a time when most long span bridges were being built of post tension concrete deck design. This use of steel allowed a significant cost saving over alternatives methods, but become controversial after three serious disasters, when new bridges collapsed in 1970 (West Gate Bridge and Cleddau Bridge) and 1971 (South Bridge (Koblenz)). Fifty-one people were killed in these failures, leading in the UK to the formation of the Merrison Committee. The report of the Merrison committee resulted in the temporary closure of two of the carriageways on the lower deck and two on the upper deck, the installation of extra steel strengthening bands around the bridge's support columns and other works which were completed in 1983. A further program of strengthening was completed in 2006. The recent works to strengthen the bridge were a very complex operation, with a lot of the work happening inside the box beam spine. The works took over 3 years and cost £82 million (14 times the original bridge building cost). The strengthening project won the British Construction Industry Awards' Major Project Award in 2005.

Although originally designed to carry 6 lanes, during the strengthening work the M1 was permanently reduced to 4 lanes following an EU directive on load bearing capacity to allow for the introduction of 40-ton trucks in the UK. This arrangement allows the third lane in each direction to join from Junction 34 to make the very busy junction safer.

The viaduct is balanced on rollers to allow for thermal expansion and contraction, and the route weaves slightly in order to make its way past obstacles. The viaduct, due to its construction, is very flexible. Movement may be felt on the lower deck as the traffic passes overhead. The Meadowhall Shopping Centre lies in the valley to the west; to the east is the Blackburn Meadows sewage works.

Tinsley cooling towers

Main article: Blackburn Meadows Power Station

Demolition of Tinsley cooling towers on 24 August 2008.

The viaduct is one of Sheffield's most prominent landmarks, and was once made all the more so by the adjacent pair of cooling towers that were left standing for safety reasons after the demolition of the Blackburn Meadows Power Station. The cooling towers were a major point of contention over the years and were once saved from destruction only after being chosen as a nesting site by a rare bird. More recently, plans were made to turn them into a piece of public art. Other plans for the towers included concert halls, skate parks and a theme park.

Their iconic status, and the possibly prohibitive costs of demolishing the towers safely, until recently looked to have cemented their status in Sheffield's future as much as they were a part of its history, until the owner of the tower (and the now-demolished power station) E.ON UK, stated its intention to demolish them once the strengthening of the viaduct made it feasible.

The 250 feet (76 m) towers were demolished at 03:00 BST on 24 August 2008 though a significant portion of the north tower remained standing for a short while. The demolition attracted widespread attention. A viewing platform was set up so the public could watch the demolition. Part of the site is proposed to be used for a new biomass power station by the owners E.ON UK.

In popular culture

The Tinsley Viaduct was 'ground zero' for a fictional Soviet Union nuclear strike on Sheffield depicted in Threads (1984), a depiction of what might have happened had NATO and the Soviet Union entered conflict over hypothetical instability in Iran, which escalated into full nuclear war. In the ensuing nuclear exchange, a one megaton nuclear missile detonates above the Tinsley Viaduct, devastating most of surrounding Sheffield.

See also

• List of bridges in the United Kingdom

External links

• Go sheffo: Cooling the Towers Cooling towers public art competition held in 2005.
• Standing on the Shoulders of Giants Blackburn Meadows cooling tower climb