The judges commended the bridge’s ‘careful refurbishment in a modern context’, reflecting DavyMarkham’s use of advanced 3D modelling and finite element analysis software on the project, and noted how the engineering restoration ‘brought back to life a fine example of Victorian innovation and creativity’. The client was Kingston upon Hull City Council and its urban regeneration company, Citybuild, while the consulting engineer was London-based Pell Frischmann.

Originally constructed in 1840 and used to convey carts and wagons from the docks to the goods station, Wellington Street Bridge is a single span, double-leaf, balanced asymmetric cast iron swing bridge, carrying a two-way carriageway with a footpath on each side, and is now a Grade 2 listed structure. Each bridge leaf is supported on a slewing mechanism and, when opened for shipping, they rotate 90 degrees and are recessed into tail wells in the lock walls. The original superstructure comprised six cast iron trusses or girders, with a 4” thick timber deck and folding metal handrails, but severe deterioration led to the bridge’s closure to all traffic in the 1980’s.

Having dismantled the bridge and transported the components to its Sheffield works, DavyMarkham found that corrosion caused by 165 years’ exposure to salt water spray had taken its toll on the structure, not least because the quality of 19th century castings was not the equal of modern foundry practices, with the inclusion of highly corrosive elements accelerating the deterioration. There were also issues with levelling and the location of the bearing units, since the axis was not in the geometric centre of each leaf, so sophisticated laser-based measuring technology was used to identify the true centre of the pivot points.

A major inspection of the structure involved the creation of a detailed 3D computer model, to analyse the construction and assess the viability of increasing its live load capacity to 7 tonnes. Each component was then metallurgically examined and replacement parts fabricated by DavyMarkham to the exact size of the original pieces. In-house FEA techniques were used in the design of the new girders, which were cosmetically identical to the cast iron originals, but of an acceptable structural strength. The wooden deck was also replaced by more modern materials, with timber cladding applied to the running surface to preserve its authentic character.

DavyMarkham also undertook a complete overhaul of the damaged and worn slewing mechanisms, at the same time mechanising the operation using invertor-controlled electric motors and gearbox units. Modern multi-roller bearings, capable of withstanding harsh environmental conditions, were used to pivot the bridge leaves, while meshing the original pinion gear drives with precision-machined modern gears was another technical challenge. When completed the whole bridge was test assembled in DavyMarkham’s workshops, before being transported in manageable sections to the Hull site.

The aim of the project was to restore the bridge to fully working order, whilst retaining as far as possible the original appearance of the structure, and DavyMarkham’s successful achievement of this goal helped gain this notable award. The reopening of the swing bridge has re-established a route across the dock and removed a major obstacle to the regeneration of Hull’s waterfront, at the same time restoring a valuable local landmark.