High Level Bridge

From Wikipedia, the free encyclopedia

For other uses, see High Level Bridge (disambiguation).

Image:High Level Bridge - Newcastle - circa 1852.jpg Image:High Level and Low Level bridges - Newcastle - 1861.jpg

The High Level Bridge, towering above the Swing Bridge across the River Tyne; photograph facing Newcastle

The High Level Bridge is a notable road and railway bridge spanning the River Tyne between Newcastle upon Tyne and Gateshead in North East England.

Designed by Robert Stephenson and built between 1847 and 1849, it is the first major example of a wrought iron tied arch or bow-string girder bridge. It is a fine and long standing engineering solution to a difficult problem; the spanning of 1337 feet of river valley, including 512 feet across water. The High Level Bridge has six river spans of 125 feet (38 m) length, sitting on masonry piers, 46 by 16 feet in section and up to 131 feet (40 m) height. There are also four land spans on each side, of 36 feet 3 inches. The single carriageway road and pedestrian walkways occupy the lower deck of the spans, 85 feet above the high water mark, and the railway the upper deck 112 above the high water mark. The total weight of the structure is 5,000 tons.<ref name=Norrie>Charles Matthew Norrie (1956). Bridging the Years - a short history of British Civil Engineering. Edward Arnold (Publishers) Ltd.</ref><ref name=Measom>George S. Measom, The Official Illustrated Guide to the Great Northern Railway, 1861, Griffin Bohn, London</ref>

According to a contemporary encyclopedia:<ref name=cyclopædia>G. Long, editor. The penny cyclopædia, 1863, Society for the diffusion of useful knowledge.</ref>

Each river span is crossed by four main cast iron arched ribs, with horizontal tie bars. The roadway is situated between a pair of ribs some 20 feet apart; and walkways are sited on either side of the roadway in a 6 foot gap between the central and outside ribs. The upper, railway, platform, rests on the arches of the ribs, whilst the lower roadway is suspended from the ribs on wrought iron rods. Each arched rib was cast in five sections. Besides the tie-bars, the ribs are braced by horizontal and vertical bracing frames, while diagonal bracings are inserted in the spandrels, or spaces between the arches and the girders which carry the railway. On the tops of the spandrel pillars, girders extend length-wise, from which other stretch at right-angles across the arched ribs. The whole thus has a perfectly rigid character and is found to bear the heaviest weights without deflection.

The bridge was built for the York, Newcastle and Berwick Railway, and together with Stephenson's Royal Border Bridge at Berwick upon Tweed, completed the line of a London-Edinburgh railway nowadays known as the East Coast Main Line. It was opened in September 1849 by Queen Victoria.

It is worth remarking that there were competing plans - not taken forwards - for a low level bridge; in 1836 Richard Grainger with engineer Thomas Sopwith proposed a crossing 20 feet above highwater mark, running the Newcastle & Carlisle, Great North of England and Brandling Junction railways into a low level terminus. Under their plans, the Scotland railway would follow contour lines to the east and north, whilst the Carlisle line would be taken up inclined planes.<ref name=Grainger>Richard Grainger, A proposal for concentrating the termini of the Newcastle and Carlisle, the Great North of England, and proposed Edinburgh railways; and for providing spacious and eligible depots, with convenient access, from these several railways to the town of Newcastle, submitted to the consideration of the respective companies, and to the proprietors of property. Newcastle, 1836</ref>

Stephenson's High Level Bridge was designed after, but completed before his more famous and equally innovative Britannia Bridge (constructed 1846-50) over the Menai Strait; it can be seen as a second and more elegant version of the Britannia Bridge, and was to influence Isambard Kingdom Brunel in his design of the Royal Albert Bridge (1855; constructed 1859) across the River Tamar at Saltash.<ref name=Norrie />

The High Level Bridge began to vibrate like a piece of thin wire<ref name=vibrate>Great Conflagration and Explosion at Newcastle and Gateshead in The Illustrated London News, October 14th 1854</ref>, but provided an excellent vantage point for the Great fire of Newcastle and Gateshead in 1854.

In 1906, construction of the King Edward VII Bridge, some 500 yards to the west of the High Level Bridge, was completed. This second bridge removed the central operational weakness of the single bridge, which is that trains entering the station from the bridge had to be reversed back across the bridge when returning south.

[edit] Restoration

The bridge was closed to road traffic in February 2005 to allow essential maintenance to ensure the bridge's long-term future, including replacement of wooden supports beneath the road deck. It was expected to reopen in late-2005, however, the reopening has now slipped as severe cracks were found in some of the bridge's iron girders. Having assessed the bridge, engineers have decided a crash barrier on each side of the roadway is necessary, meaning that there will be space for only one lane of traffic when the bridge reopens. Hence there is speculation that the bridge could either be made one way, or controlled by traffic lights, the possibility of it being bus only route has also been mentioned.

In September 2006, the target date for re-opening was revised to Summer 2008,<ref name=beeb1>Bridge closed for two more years, on the BBC News website, last updated Monday, 18 September 2006, retrieved 21 September 2006</ref> the second further delay announced in six months. The boss of local bus company Go North Eastern has claimed it may not open again until 2010,<ref name=icnewcastle1>Bridge could be closed until 2010, on icnewcastle, the website of the Newcastle Chronicle and Journal, May 6 2006, retrieved 21 September 2006</ref> but this has been strongly refuted by Network Rail, which owns the bridge.

In March 2006, the footpath of the bridge, which has been kept open during the restoration project, was closed following repeated vandal attacks.<ref name=icnewcastle2> Bridge path set to close on icnewcastle, the website of the Newcastle Chronicle and Journal, Feb 9 2006, retrieved 21 September 2006</ref>