The Humber Bridge

Suspension Bridge, built 1973 to 1981 for the Humber Bridge Board. The consulting engineers were Freeman Fox & Partners with Bernard Wex as partner-in-charge, and the consultant architect was R E Slater. The main contractors for the superstructure were British Bridge Builders Ltd, a consortium comprising Sir William Arrol, Cleveland Bridge and Engineering, and Redpath Dorman Long. John Howard & Company Ltd were the main consultants for the substructure and towers. The administration building, garages, stores, toll booths and associated canopies are not included in the listing.

The bridge is built of reinforced concrete, steel panels, and high tensile steel wire cables. It carries a dual two-lane carriageway with footpaths and cycle tracks across its deck.

The bridge has two concrete towers, each with tapered, hollow legs and four horizontal, portal beams, the lowest of which sits immediately beneath the road deck. The corners of the legs and beams are rounded. Slip-formed construction means there is a lack of obvious joints. The legs contain maintenance lifts and access ladders.

The north Hessle tower stands on a reinforced concrete slab 44 metres long by 16 metres wide and 11.5 metres deep, founded about 8 metres down in chalk. The south Barton tower stands on a concrete pier about 16 metres deep, supported on twin hollow circular caissons, each 24 metres in diameter, which penetrate into Kimmeridge Clay to a depth of 8 metres.

At both ends of the road deck are massive concrete anchorages. The side walls above ground comprise five inclined and projecting blocks, giving a stepped profile, decorated with inclined bands of narrow, projecting concrete ribs. The inner and outer faces are decorated with horizontal, projecting blocks. Inside, each anchorage contains two chambers where the main cables are supported by steel saddles before splaying out into separate strands that fit over strand shoes, retained by pre-stressed rods into the anchor blocks at the backs of the chambers. The north bank anchorage weighs 190,000 tonnes, measures 65.5 metres long by 36 metres high, and is founded about 21 metres below ground level. The south bank anchorage, weighing 300,000 tonnes, is similar but is supported on a cellular structure built within a framework of diaphragm walls founded 35 metres below ground level in Kimmeridge Clay.

The road deck comprises 124 streamlined, hollow box sections built of stiffened steel plate panels. The box sections are 22 metres wide and 4.5 metres deep with 3-metre-wide panels along each side which are lower than the road carriageway and cantilever outwards to carry the footpaths and cycle tracks. The carriageway has outer and central crash barriers formed of four horizontal, high-tensioned steel cables bolted at regular intervals to rectangular steel posts. The angled sides to the carriageway contain small, oval inspection hatches. The outer edges of the footpath and cycle track have steel handrails with closely spaced tubular railings.

Each main cable comprises 37 strands, each of 404 wires, with an additional 800 wires to the cables above the north side span. The cables are strapped and wrapped, with hanger clamps fixed at regular intervals onto which 242 high tensile steel hangers supporting the road deck are attached. Dehumidifiers have been added to the cables to combat corrosion.

A movable maintenance gantry, now no longer in use, is slung beneath the road deck.