Severn Bridge
The Severn Bridge is a motorway suspension bridge that spans the River Severn between South Gloucestershire in England and Monmouthshire in South East Wales. It is the original Severn road crossing between England and Wales, and took three and a half years to build, at a cost of £8 million. It replaced the 137-year-old Aust Ferry.
The bridge was opened in 1966 by Queen Elizabeth II. For thirty years, the bridge carried the M4 motorway. It was granted Grade I listed status in 1999.
Following the completion of the Prince of Wales Bridge, the section of motorway from Olveston in England to Magor in Wales was designated the M48.
In addition to carrying the motorway, the bridge has service paths on each side which are open to pedestrians and cyclists. These carry National Cycle Route 4 and EuroVelo cycle routes, as well as hosting a weekly parkrun.
History
The first proposal for a bridge across the Severn, approximately in the same location as that eventually constructed, was in 1824 by Thomas Telford, who had been asked to advise on how to improve mail coach services between London and Wales. No action was taken, and over the next few decades the railways became the dominant mode of long-distance travel, with the Severn Railway Bridge at Sharpness being opened in 1879 and the main line Severn Tunnel in 1886.The growth of road traffic in the early 20th century led to further calls for improvements, and in the early 1920s Chepstow Urban District Council convened a meeting of neighbouring local authorities to consider a Severn crossing to ease congestion and delays on the A48 passing through the town. In 1935 Gloucestershire County Council and Monmouthshire County Council jointly promoted a parliamentary bill to obtain powers to build the bridge over the estuary, with 75% of costs to be met by the Ministry of Transport from the Road Fund. The bill was rejected by Parliament after opposition from the Great Western Railway Company.
After the Second World War, plans began to be made for a nationally funded network of trunk roads, including a Severn Bridge, for which the contract was awarded to Mott, Hay and Anderson, with Freeman Fox and Partners. The public inquiry into the scheme was held on 24 September 1946 at Bristol University. Because Government funding was prioritised for the similar Forth Road Bridge, construction of the Severn Bridge was not started until 1961: the UK government announced in 1962 that construction costs would be recovered by a toll of 2s 6d on all vehicle crossings, though walking or cycling across the bridge would be charge-free. The substructure was completed by contractors John Howard and Co in 1963. The superstructure contract was awarded to Associated Bridge Builders Ltd in 1963, and completed in 1966.
The bridge has been featured in several promotions.
In January 1977, it was announced that bridge traffic would be restricted to a single lane in each direction following the discovery of several weaknesses in the ten-year-old structure. The lane closures would last for several months.
The Severn Bridge crossing was strengthened and resurfaced in the late 1980s as the weight of traffic grew. The work included the strengthening of the Severn Bridge towers and deck, an extension to the Wye Bridge towers and the replacement of the original single stays with two stays. The open structure of the new stays is designed to facilitate maintenance. Most of the strengthening work was inside the deck box and towers and so is not visible. Design of the strengthening was by Flint & Neill. The surfacing is a thick layer of mastic asphalt over an acrylic waterproofing membrane.
During its 40th year of operation in 2006, the bridge was inspected to check for corrosion of the suspension cables. According to the Highways Agency, the inspection concluded that the bridge needed restrictions on heavy goods vehicles. Such vehicles were subsequently restricted to one lane on the bridge, with weight restriction signs in place. A system of rubber casing on the cables with dry air circulation, as used on the Forth Road Bridge, was installed in 2007–2009 in a move to halt the progress of the corrosion.
In October 2021, the Welsh Government announced it was considering reclassifying the M48 into an A-road in view of the reduced amount of traffic on the bridge and M48 following the opening of the Prince of Wales bridge, and the high cost to improve the M48 to motorway standards. Reclassification requires approval from both the Welsh Government and Secretary of State for Wales, with the Department for Transport stating they have no plans to reclassify the M48 in England.
In May 2025, after laboratory tests of corroded cable strands found some had less strength than expected, most HGV traffic over was banned from the crossing for a trial period of 18 months. According to National Highways, "the medium-term solution aims to lift the 7.5T restriction by combining technology and traffic management tools these will ensure vehicle loads remain within safe limits at all times."
Construction
Construction started in May 1961; construction of the superstructure started 12 months later. At the time, there was also discussion in Liverpool of a similar suspension bridge over the River Mersey. The first construction equipment arrived on the banks of the Severn on Monday 17 April 1961, at Beachley and Aust. Equipment of John Howard Ltd would arrive by train at Chepstow railway station, from the Forth Road Bridge site. The same equipment for making the cables on the Forth Road Bridge was brought down to the Severn site.The bridge parapet, with two miles of railing and 1,200 steel safety barrier posts, was built by Bayliss Jones & Bayliss, part of GKN, of Cable Street, Wolverhampton. Bayliss Jones also built the parapet for the M2 Medway Viaduct, and the M1 Tinsley Viaduct.
Zinc wire was manufactured by Charles Clifford Ltd of Dogpool Mills in Stirchley, Birmingham, for protection of steel fabrications. In November 1962, Dorman Long of Middlesbrough received an order for 4,200 tons of galvanised high-tensile steel wire, of 0.196 inches in diameter. The first cables were constructed in late October 1963. A walkway across the towers was established by January 1964. The main construction of the cable across the Severn began in mid-February 1964. The cables were floodlit in March 1964. Ernest Marples, Minister of Transport, walked across the cable structure from Gloucestershire to Monmouthshire, on Monday 22 June 1964. The cables were complete on Thursday 9 July 1964. It had taken four months, with fifty workmen.
The first 130-ton road section was lifted into place on Tuesday 27 October 1964, on the 'Severn Knave' barge. There were four barges, Severn Queen, Severn King, Severn Knave and Severn Princess. It was the first time that bridge sections had been floated in the river, and lifted. There were 88 road sections.
In May 1966, while on his way to Cardiff, Bob Dylan was photographed waiting for Aust ferry with the almost-finished bridge visible in the background behind him. Shortly after, the bridge was officially opened on 8 September 1966 by Queen Elizabeth II.
For the Gloucestershire M4 approach road, a contract of £2,374,140 was given to Costain in August 1963, for four miles of dual carriageway. For the Monmouthshire M4 approach road, a contract of £1,677,564 was given to Martin Cowley Ltd of Clay Cross in Derbyshire, in March 1964, for four miles of dual carriageway.
Construction of the Wye Bridge started in June 1963.