Silver Jubilee Bridge

History

Until 1868, when Runcorn Railway Bridge was opened, the only means of crossing the Mersey at or near Runcorn Gap were by fording or by ferry. Before that the lowest crossing of the river had been the road bridge at Warrington. The first bridge to carry vehicular traffic across Runcorn Gap was the Widnes-Runcorn Transporter Bridge which opened in 1905. This was an inefficient means of transport and it had become inadequate for the amount of traffic using it before the outbreak of the Second World War. In 1946 the Ministry of Transport agreed that the transporter bridge should be replaced when sufficient funds were available. Mott, Hay and Anderson were appointed as consultant engineers.

Planning

The new bridge had to allow the passage of shipping along the Manchester Ship Canal. Many ideas were considered, including a new transporter bridge or a swing bridge. These were considered to be impractical and it was decided that the best solution was a high-level bridge upstream from the railway bridge. This would allow the least obstruction to shipping and would also be at the narrowest crossing point. The first plan for a high-level bridge was a truss bridge with three or five spans, giving an 8 yards (7 m) dual carriageway with a cycle track and footpaths. This was abandoned because it was too expensive, and because one of the piers would be too close to the wall of the ship canal. The next idea was for a suspension bridge with a span of 343 yards (314 m) between the main towers with an 8 yards (7 m) single carriageway and a 2-yard (2 m) footpath. However aerodynamic tests on models of the bridge showed that, while the bridge itself would be stable, the presence of the adjacent railway bridge would cause severe oscillation. The finally accepted design was for a steel through arch bridge with a 10-yard (9 m) single carriageway. The design of the bridge is similar to that of Sydney Harbour Bridge but differs from it in that the side spans are continuous with the main span rather than being separate from them. This design feature was necessary to avoid the problem of oscillation due to the railway bridge. The main span measures 361 yards (330 m) and each side span is 83 yards (76 m).

Construction

Construction began on 25 April 1956. The contractors for the first phase of work, Leonard Fairclough of Adlington, cleared the ground and constructed the foundations for the piers. The contract for the second phase, the building of the main arch and the side arches, was given to Dorman Long of Middlesbrough who sub-contracted the building of the bridge deck, viaduct and roadworks to Leonard Fairclough. Building of the bridge itself began in March 1958 and the side spans were completed by November 1959. The main arch was built by cantilevering steelwork from the side spans until it met in the middle in November 1960. The carriageway was suspended from the arch by 48 lock-coil wire ropes. From February 1960 approach roads and viaducts were being built on both sides of the river; the total length of viaduct constructed was 525 yards (480 m). The approaches on the Runcorn side blocked the Bridgewater Canal at Waterloo Bridge and the line of locks leading down to the Mersey were filled in. The bridge was officially opened on 21 July 1961 by Princess Alexandra.

Statistics

The main arch is 361 yards (330 m) long and each side arch measures 83 yards (76 m). During its construction 720,000 rivets were used. Its height over the river bed is 285 feet (87 m) and the headroom over the ship canal is 80 feet (24 m). During its construction 5,900 tons of steel were used and 7,500 tons of concrete. The bridge requires constant repainting and for this one coat uses 6,000 imperial gallons (27,277 l) of paint. On the Runcorn side, the approach viaducts are 359 yards (328 m) in length, and on the Widnes side 166 yards (152 m). The cost of constructing the bridge was £2,433,000. At the time of its construction it had the third longest steel arch span in the world. It had the longest vehicular span in the country, but this record was held for only a few weeks until the Tamar Bridge was completed. By 2001 it was the 10th longest steel arch bridge, and at that time was just 8 inches (20 cm) short of having Europe's largest span.

Consequences

The bridge transformed Runcorn from an effective cul-de-sac into a town with through traffic. Road communications between north Cheshire and south Lancashire were immediately improved. Trade at the Port of Runcorn increased sixfold between 1960 and 1970. Its presence enabled the development of the New Town in Runcorn in the late 1960s and the 1970s. The amount of traffic using the bridge trebled between 1961 and 1970. This led to such severe congestion that in 1975 the bridge was widened and the approach roads were improved. The carriageway was widened to incorporate the footpaths, giving it four lanes and a cantilevered footway was built on the east side of the bridge. This was completed in 1977 and in that year the bridge was renamed from Runcorn Bridge to the Silver Jubilee Bridge to commemorate the Queen's Silver Jubilee. Since 1994 the bridge has been illuminated at night by floodlights. Repairs to chloride corrosion of the bridge's deck were carried out in the early 21st century using an innovative electrolytic method; they were shortlisted for the Prime Minister's Award for Better Public Building of 2010.

Traffic on the bridge has continued to grow to over 80,000 vehicles a day, and there is frequent congestion. In order to alleviate this, a further crossing is being built, known as the Mersey Gateway. This is a six-lane toll bridge to the east of the Silver Jubilee Bridge to be completed in September 2017. Following completion of the Mersey Gateway, the Silver Jubilee bridge will be closed to cars for a year for maintenance, after which it will reopen with tolls applied to both bridges.