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Selby Swing Bridge (Selby Toll Bridge)
River Ouse, Selby, West Yorkshire, UK
associated engineer
E.W.H. & Partners Gifford
date  1791, 1969 - 1970
era  Georgian  |  category  Bridge  |  reference  SE616325
ICE reference number  HEW 784
The present operational swing bridge carrying the A19 over the River Ouse at Selby is a modern replacement for an 18th century timber swing bridge. Its unusual construction combines a steel and timber deck with a timber substructure. Originally a toll bridge, it caused many years of road traffic congestion until the A63 Selby bypass opened in 2004.
The River Ouse is tidal at Selby, with a spring tide range of around 9m, and tidal race speeds of 7-8 knots (13-15km/hr). From about 1260, a ferry was the only means for traffic to cross the river here, and most shipping continued upriver north to York. When the Selby Canal, designed by William Jessop (1745-1814), opened in 1778 it brought considerably more trade to the town.
The need for a permanent bridge crossing soon became pressing. In 1789, Jessop reported on the matter, to much opposition from ferries and river navigation companies who feared loss of income — though local residents and manufactures were in favour. Jessop’s recommendations were implemented only after an independent census of river and ferry traffic was carried out. The report of 18th November 1790 showed that in a single year 105,000 pedestrians, 75,000 horses, 30,000 farm animals and 500 vehicles had used the ferries.
A tolled swing bridge was duly authorised by the Selby Bridge Act 1791 — An Act for building a Bridge near the Ferry over the River Ouze, from Selby, in the West Riding of the County of York, to the opposite Shore, in the Parish of Hemingborough, in the East Riding of the said County. An opening span of not less than 30ft (9.1m) for river traffic was specified. The proprietors were allowed to claim the toll revenues from pedestrians and vehicles tax-free. River traffic passing under the bridge had right of free passage.
Among the "Company of Proprietors of Selby Bridge" were Jessop, John Carr (1723-1807), John Smeaton (1724-92), Thomas Atkinson (1729-98) and Robert Whitworth (1734-99). At least two of these distinguished engineers and architects were consulted on the bridge’s design and construction.
The 60m long oak bridge had eight spans carried on timber trestles, with a clear road width of about 5.6m. Each trestle consisted of a row of piles topped by a massive crosshead beam. The main longitudinal deck beams, spanning up to 8.8m, were supported on hammerhead beams over the trestles. Between trestles, the northern Spans 1-3 averaged 6.2m, Span 4 was 11m — opening to a clear waterway of 9.45m — and the southern Spans 5-8 averaged 7.5m. The swing span pivoted on ball bearings and was operated manually with a windlass.
A model of the original bridge, used during the Parliamentary proceedings for the 1791 Act, can still be seen in the Science Museum in London. The bridge company owns a model of the swing span, as reconstructed in 1921 following a major accident. Sometime in the 1920s, a 6.1m diameter turntable was installed beneath Span 3, which operated the swing span. In 1929, deck works were under taken on Spans 3 and 4.
In 1955, the bridge proprietors consulted E.W.H. Gifford & Partners about maintenance and repairs. Additional timber trestles were piled adjacent to the originals to provide increased deck support for Spans 5-8. At Span 5, the deck was renewed and new full-span timber beams installed. In 1960 and 1963, additional support trusses and trestles were installed on Spans 1 and 2. At some stage, the road width was increased to 6.4m.
In 1966, a survey showed that continuing repair was no longer economic and the following year Gifford was retained to design a replacement structure. The £130,000 contract was completed during an 18-month period during 1969-70. When demolished, the original bridge was the last 18th century timber trestle bridge to carry trunk road traffic.
During the construction period, on 7th August 1968, a ship collision closed the bridge (then carrying the A63 road) for three weeks and traffic faced a 48km detour.
The new five-span bridge was built around the old one, in two halves longitudinally, using a derrick running on a temporary timber gantry. The new structure was designed and verified by model testing to be stable at half width. Timber was used as the main structural material wherever possible, including re-using some of the existing piles, to retain the spirit of the original bridge. Road and river traffic were maintained during most of the reconstruction, with road traffic using a Bailey bridge while the swing span steelwork was being assembled underneath.
The four bridge supports are formed from a row of loadbearing piles, or bents, with protective fendering. Each bent has eight hewn Greenheart piles nominally 406 x 406mm and 21.3m long, cross-braced for 4.1m with 305 x 152mm Opepe timbers and capped by a steel I-beam crosshead. The central six piles of a bent are vertical but the outer ones are driven at a batter of 1 in 8 to resist lateral forces. The bents on either side of the turntable, supporting the swing span, are also braced together longitudinally to provide torsional rigidity. All timbers are through bolted with 25mm or 32mm diameter galvanised bolts.
Pitch pine fender piles, 381 x 381mm and 15.2m long, surround the two southern pile bents, with triangular dolphins at each end, and form a single row on the south side of the turntable. Fenders are driven at 4m centres and are braced horizontally, at 1.2m centres, and diagonally but are not connected to the rest of the structure, preventing force transference.
Each of the abutments consists of a steel sheet piled wall topped by a reinforced concrete capping beam. The Selby (south) abutment is tied back to a reinforced concrete anchor beam and the Barlby (north) abutment is in cantilever.
The bridge superstructure is of steel with timber decking and three-rail steel parapets on each side. The two 13.7m southern spans have eight 762 x 267mm steel I-beams weighing 147kg/m, set at 1.2m centres with channel-section diaphragms at midspan and quarter points. In situ connections were made with 19mm diameter high-strength friction grip bolts.
The 32.6m long moving part of the bridge deck covers most of the three northern spans. Here the positions of existing pile bents dictated the new substructure layout. The circular turntable is above the middle one of the three spans and 3.05 tonnes of kentledge provides balance to the shorter northernmost span. On each side of the bridge, in line with the centre of the turntable, a steel A-frame with a hydraulic jack at its apex rises about 2.5m above the deck to carry pairs of 51mm diameter steel tie rods to the ends of the swing span.
The swing span can move in either direction, taking two minutes to rotate 90 degrees and providing clear navigation channels of 11m on each side. It is powered by a 9kW electric motor and chain drive mounted between the main beams, which can be accessed from beneath the footway. Reactions to motion forces are carried on four roller bearings atop the turntable, with a central bearing to take out of balance shear forces. The ends of the opening span rest on spheroidal graphite iron bearings.
Timber decking consists of laminated panels of Douglas Fir 5.4m long, 813mm wide and 140mm thick. The 6.7m wide two-lane roadway has Opepe kerbs and a wearing surface of 19mm Finnish Birch plywood topped with calcined bauxite chippings in an epoxy resin matrix. The 1.5m wide single footway has a Keruing timber surface.
In 1970, the traffic lights at either end of the bridge were controlled from the Toll House (SE617325), though the barriers were operated manually. The swing span was controlled remotely from the same building. Since the bridge opened, extra fendering has been installed to protect the swing span piers (date unknown). In 1979, the bridge suffered two ship collisions in two days, causing £4,000 worth of damage.
In September 1991, tolls were abolished after the bridge was purchased by Selby District Council and North Yorkshire County Council, aided by contributions from local businesses. In 2004, the long-awaited Selby bypass opened, providing an alternative route over the River Ouse and easing congestion on the bridge.
Between January and July 2011, bridge repairs costing around £350,000 were undertaken. Work included refurbishment and selective replacement of the steel deck beams, and carriageway drainage.
Contractor (1969-70): Yorkshire Hennebique Contracting Company Ltd
Swing mechanism (1969-70): Joseph Westwood Ltd
Timberwork (1969-70): Mallinson & Ecersley
Laminated deck panels (1969-70): Kingston Architectural Ltd
Road surfacing panels (1969-70): Acem Flooring Ltd
Research: ECPK
"Design and Reconstruction of Selby Swing Bridge, Yorkshire" by M.V. Woolley, in The Highway Engineer, Vol.20, No.1, pp.14-23, January 1973
reference sources   CEH NorthBDCE1

Selby Swing Bridge (Selby Toll Bridge)