The Royal Albert Bridge is a railway bridge which spans the River Tamar in England, between Plymouth, Devon and Saltash, Cornwall. Its unique design consists of two lenticular iron trusses above the water and conventional plate-girder approach spans. Its total length is . It carries the Cornish Main Line railway in and out of Cornwall and is adjacent to the Tamar Bridge, which opened in 1961 to carry the A38 road.

The Royal Albert Bridge was designed by Isambard Kingdom Brunel. Surveying started in 1848 and construction commenced in 1854. The first main span was positioned in 1857 and the completed bridge was opened by Prince Albert on 2 May 1859. Brunel died later that year and his name was then placed above the portals at either end of the bridge as a memorial. During the 20th century, the approach spans were replaced, and the main spans strengthened. It has attracted sightseers since its construction, appearing in many paintings, photographs, guidebooks, postage stamps and on the UK's £2 coin. Anniversary celebrations took place in 1959 and 2009.

Cornwall Railway

Two rival schemes for a railway to Falmouth, Cornwall, were proposed in the 1830s. The 'central' scheme was a route from Exeter around the north of Dartmoor, an easy route to construct but with little intermediate traffic. The other, the 'coastal' scheme, was a line with many engineering difficulties but which could serve the important naval town of Devonport and the industrial area around St Austell. The central scheme was backed by the London and South Western Railway while the coastal scheme was promoted by the Cornwall Railway and backed by the Great Western Railway which wanted it to join up with the South Devon Railway at Devonport. The Cornwall Railway applied for an Act of Parliament in 1845 but it was rejected, in part because of William Moorsom's plan to carry trains across the water of the Hamoaze on the Devonport-to-Torpoint Ferry. Following this Isambard Kingdom Brunel took over as engineer and proposed to cross the water higher upstream using a bridge at Saltash instead. The Act enabling this scheme was passed on 3 August 1846.

Design

thumb|left|A drawing of one span and its piers

thumb|upright|left|Section of a truss between the tube and the deck

The structure was the third in a series of three large wrought iron bridges built in the middle of the 19th century. It was influenced by the preceding two, both of which had been designed by Robert Stephenson. The two central sections of Brunel's bridge are novel adaptations of the design Stephenson employed for the High Level Bridge across the River Tyne in Newcastle Upon Tyne in 1849. Brunel was present when Stephenson raised the girders of his Britannia Bridge across the Menai Strait in the same year. From 1849 to 1853 Brunel was erecting an iron bridge of his own; the Chepstow Railway Bridge carried the South Wales Railway across the River Wye and featured a main truss of with a curving tubular main member and three conventional plate-girder approach spans of , a similar solution to that adopted for crossing the River Tamar at Saltash.

The river is about wide at Saltash. Brunel's first thoughts had been to cross this on a double track timber viaduct with a central span of and six approach spans of with clearance above the water. This was rejected by the Admiralty, who had statutory responsibility for navigable waters, so Brunel produced a revised design to give clearance, with two spans of and two of . The Admiralty again rejected this plan, stipulating that there should not be more than one pier in the navigable part of the river.

Brunel now abandoned plans for a double track timber structure and instead proposed a single track wrought iron design consisting of a single span. As the cost of this structure would have been around £500,000 at 1846 prices (equivalent to £ in ), he amended the design to one of two main spans of with clearance above mean high spring tide; this was approved by the Admiralty and the directors of the Cornwall Railway.

The two spans are lenticular trusses with the top chord of each truss comprising a heavy tubular arch in compression, which tend to expand in length under load, while the bottom chord comprises a pair of chains, which tend to contract in length under load. By design, these two effects cancel so that there is no net change in length under load. This in turn enables each of the trusses to be supported with no horizontal thrust exerted on the piers, which is crucial in view of the curved track on either side. Between these two chords are supporting cross-bracing members and suspension standards which hang beneath the bottom chord to carry the railway deck which is a continuous plate beam. There are also 17 shorter and more conventional plate-girder approach spans on the shore. On the Cornish side there are ten which measure (from Saltash station towards the river): , five of , , , , , and seven on the Devon side (from the river towards St Budeaux): , , , and three of . This gives a total length for the nineteen spans of . Illness prevented the attendance of Brunel who was instead represented by his chief assistant Robert Brereton. The walkways had previously been temporarily removed in 1959 and the bridge floodlit during its centenary year.

Additional links between the suspensions chains and the decking were added in 1969 to further strengthen the bridge.

Cultural impact

thumb|Bench seat at the [[Brunel Museum, Rotherhithe, London incorporating a model of the bridge with a train]]

The construction of such a large and distinctive bridge soon caught the attention of the general public. The launching of the Cornish span in 1857 attracted a crowd of around 20,000, It has also been the subject of many photographs and postcards.

It was already a feature in guidebooks in the year of its opening: "It is a labour of Hercules, but Mr Brunel has accomplished the feat," proclaimed one, and went on to report in detail the design and construction of the bridge that "for novelty and ingenuity of construction stands unrivalled in the world". More than 100 years later it continues to appear in many travel guides and features. John Betjeman summed up its impact on the traveller:

<blockquote>The general grey slate and back gardens of Plymouth, as seen from the Great Western made the surprise of Saltash Bridge all the more exciting. Up and down stream, grey battleships were moored in the Tamar and its reaches. Hundreds of feet below, the pathetic steam ferry to Saltash from the Devon bank tried to compete with Brunel's mighty bridge.</blockquote>

The bridge has become a symbol of the transition from Devon to Cornwall. In the Great Western Railway's The Cornish Riviera travel guide, SPB Mais regarded it as "an almost magic means of transporting travellers from a county, which, if richer than others, is yet unmistakingly an English county, to a Duchy which is in every respect un-English. You shut your eyes going over the Saltash Bridge only to open them again on a foreign scene".

The bridge is the backdrop of ITV1's The West Country Tonight during the old westcountry region.

Special events

thumb|right|A new commemorative plaque was unveiled at Saltash station on 4 May 2009 to recognise the 150th anniversary of the bridge.

Special occasions have been marked over the years by special events:

  • 1859 – The bridge was opened by Prince Albert two days before the railway was opened to the public. He arrived by special train from Windsor, was shown around the bridge and the works yard, and then left aboard the Royal Yacht.

References

Further reading

  • The Royal Albert Bridge official website with Live Webcam
  • A modeller's research into the bridge
  • The Brunel Museum, Rotherhithe, London
  • Photographs of the 150th anniversary events including the bridge walk and re-enactment of the opening
  • Brunel portal
  • An investigation of the first decorative scheme