| 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. |
|
| Carries | M1, A631 |
| Crosses | River Don Sheffield Canal Midland Main Line South Yorkshire Railway |
| Locale | Tinsley/Wincobank |
| Maintained by | Highways Agency |
| Design | twin deck box girder bridge[1] |
| 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) |
| Vertical clearance | 10 m (33 ft) (on the A631) |
| Clearance below | 10 m (33 ft)[2] |
| Construction begin | Spring 1965[3] |
| Construction end | 1968 |
| Opened | 25 March 1968[3] |
| Daily traffic | 100,000 vehicles/day[4] |
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.
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The viaduct was opened in March 1968[5] 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 has allowed the viaduct to be strengthened, in 1983 and again 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).
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.[6]
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.
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.[7] 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.[8]
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.[9] Part of the site is proposed to be used for a new biomass power station by the owners E.ON UK.[10]