C O N T E X T 1 3 9 : M A Y 2 0 1 5 19 The project aims to: •• Re-establish BOB’s status as an important and iconic Brunel bridge in an area of Bristol’s historic harbour which has many other interesting features. •• Develop a scheme to restore the historic structure in situ, conserve original material, and return it to working order for occasional use by pedestrians and cyclists as an alternative means of crossing the North Entrance Lock. •• Interpret the bridge in the context of the wider area and create a new destination in a neglected part of Bristol. Over the past two years dedicated volunteers, including several professional engineers, have achieved much.The history of the bridge has been thoroughly researched and early drawings reproduced.A structural engineer working as a volunteer has surveyed and drawn up all extant parts usingTrimble Sketchup Pro, comparing the extant structure with early drawings. The survey team plans to continue its detailed condition survey during 2015, including plotting the thicknesses of corroded plates using ultrasonic techniques. It will move on to calculating the extent towhich repairs will be needed to achieve adequate overall structural strength. Professional oversight will be needed at this stage.This has already started. In 2014 English Heritage offered the volunteers funding through Bristol City Council for investigations, trial repairs and design work. With matching funding, this gave a total of £41,000.This enabledMannWilliams, structural engineers of Bath, Dorothea Restorations of Bristol and other specialists to undertake a programme of works to investigate the internal condition of the hydraulic rams and trace drains, and to carry out trial patch repairs to corroded wrought-iron plates, ice-blasting, two-pack painting, friction-grip bolting and hot-set riveting.Meanwhile the volunteers have carried out trial excavations around the cast-iron bed-plate to establish the nature of its footing.This was important as the whole site is regularly inundated with sea-water during spring tides.Water is known to have been percolating through the foundations since 1873, yet no sign of settlement of the heavily-loaded bed casting has been detected. Trial works completed on site in February 2015 will allow a well-specified and costed scheme for repair to be developed to form a sound basis for fundraising. This will include an application to the Heritage Lottery Fund for Stage 1 funding. Professional support will be needed at this stage, so project sponsor the Avon Industrial Buildings Trust is currently seeking £15,000 pump-priming money. The volunteers continue work on site. A pair of new interpretation boards has been erected, and shortly a temporary felted-timber roof will be erected to protect the heavily corroded turntable area.Appeal leaflets have been printed, and there is an extensive website at www. brunelsotherbridge.org.uk. A number of guided walks and conducted tours have taken place, including during the 2014 Doors Open Day when ‘Mr Brunel’ conducted an entertaining walk from the SS Great Britain to his South Dock and ‘other bridge’. The volunteers do not underestimate the challenge of raising more than £1 million to restore a derelict structure in a rundown area of Bristol. Momentum has built over the last two years, generating considerable interest and goodwill locally, and increasingly at a national level. Much has been achieved practically on site, and a credible, costed, restoration scheme will be available soon.Whether that can attract hard cash will depend on a wider scheme to develop and interpret the local area for public benefit. It is here that engineering conservation meets politics. J327 FEBRUARY 2015 BRUNEL SWIVEL BRIDGE, BRISTOL SK401 SK401 TURNING MECHANISM PERSPECTIVE NTS GeoffWallis is a former managing director of Dorothea Restorations. He acts as a consultant on the conservation of historic metalwork and machinery, and provides the technical lead on the Brunel Swivel Bridge project. The bridge’s turning mechanism An illustration of the bridge with deck timbers omitted for clarity (courtesy of BobWatkins) A section showing part of the bridge’s structure
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