Engineering Rotational Movement Into Moving Bridge Structures

The industrial heritage of newly-renamed engineering design and manufacturing company, DavyMarkham, stretches back to 1830 and focuses on steel mills, hydroelectric power, tunnelling equipment and mine winders. Yet within the last ten years, the design, manufacture, installation and commissioning of moving bridges has emerged as a core business activity, with DavyMarkham engaged on a series of high profile bridge contracts.

Working closely alongside architects and designers, consulting engineers, civil and steelwork contractors, and client organisations, the Sheffield-based company has been involved in such key projects as the award-winning Gateshead Millennium Bridge, the distinctive Paddington Basin Helix Bridge, the arterial Selby By-Pass Swing Bridge, the Bellmouth Passage Swing Bridges and Great Wharf Road Lift Bridge at Canary Wharf, and latterly the restoration of the historic Wellington Street Swing Bridge at Hull. On each new build contract, it has applied its engineering design and fabrication skills to turn exhilarating design concepts into practical working solutions. 

While DavyMarkham has supplied tower saddles and other structural steelwork for landmark fixed suspension bridges in Hong Kong and San Francisco, it is the company’s experience of building tunnelling machinery for the Channel Tunnel, London, Moscow and Paris metros and over 450 literally ground-breaking projects that lies behind the capacity to engineer complex moving bridge structures. 

The turning and rotating technology employed in the design and fabrication of giant tunnel boring machines, as well as water turbines, cable turntables and mine hoists, is now being successfully applied to bridge decks that lift, swing and swivel. Modern finite element analysis and 3D modelling software, coupled with an in-depth knowledge of mechanical, electrical and hydraulic design disciplines, then allows precise manufacturing drawings to be originated and implemented in-house.

“Each moving bridge contract involves unique or complex technical challenges to be overcome,” says DavyMarkham Sales Director, Gordon Scott. “Our manufacturing heritage, design engineering skills and understanding of static and dynamic loads, torsion, resonance, weather and other forces imposed on bridge structures, enable architectural visions to be realised in solid steel, concrete and glass.”

Usually constructed over busy waterways where it is impractical or prohibitive to build a fixed bridge high enough to allow river traffic to pass beneath, moving or movable bridges incorporate a section of the deck that lifts, rolls or swings aside to provide additional clearance. Generally, these bridges are powered by electric motors operating winches, gearing or hydraulic cylinders and typically incorporate traffic signals for road and water traffic, as well as moving barriers for pedestrians and vehicles, which are coordinated with bridge openings by PLC-based control systems. A moving bridge is likely to be heavier and more complex than a fixed bridge of the same span, due to the mechanisms involved, but the variety of lift, swing and bascule (drawbridge) configurations offers architects and designers tremendous aesthetic scope.

Such creativity is epitomised by the rotating Helix Bridge, designed, engineered, installed and commissioned by DavyMarkham, where the overriding brief was to maintain the vision of conceptual artist Marcus Taylor. Commissioned by consulting engineers Buro Happold Mace on behalf of Paddington Development Corporation, it has the unusual tromp l’oeil effect of appearing to corkscrew across the canal. Employing perfectly synchronised lateral and rotational movement, the bridge deck travels across at 75mm/sec, while the glass/steel composite tube rotates at 3rpm, giving one helix pitch rotation every 20 seconds. The glazed structure itself consists of shaped glass panels, bonded to a corkscrew of tubular stainless steel, and the installation included PLC controls and a bridge/boat protection scheme.

Equally distinguished and elegant is the Millennium Bridge, conceived by architects Wilkinson Eyre for Gateshead Borough Council, which won RIBA’s distinguished Stirling Prize. Commissioned by consulting engineers Gifford & Partners, DavyMarkham was responsible for the main mechanical, electrical and hydraulic systems, which control the entire tilting process that earned the bridge its sobriquet, the Blinking Eye. The structure has just one major moving part, the bridge itself, and DavyMarkham also designed and manufactured the 14 tonne trunnions or hinge assemblies on which it swivels. Finite element analysis software was used to optimise the profile and material, as well as the outboard bearings, and the company also consulted Bath University on synchronising two sets of large hydraulic cylinders, one located on each bank of the Tyne.

One of the UK’s longest double-acting hydraulic cylinders, which required £20k worth of oil for the first fill, is a feature of the high profile Great Wharf Road Lift Bridge, commissioned by Canary Wharf Contractors and again designed by Wilkinson Eyre. Here, DavyMarkham undertook responsibility for the giant hydraulic ram, the hydraulic and electrical control system and associated support structure, under the management of Gifford & Partners and mechanical  & engineering consultants Bennett & Associates. The same project team was also behind the Bellmouth Passage pedestrian swing bridges, where DavyMarkham handled the complete design, manufacture and commissioning of the main bridge structures, rotating and nose-locking mechanisms, and PLC control systems. The deck structures were built to a calculated pre-camber and during construction ballast was used to compensate for the eventual weight of the glazed passageway and superstructure, installed subsequently on site.

One of the largest moving structures of its kind, the cable-stayed Selby Swing Bridge features a 98m span, 1200 tonne  central span that rotates on a central pivot to allow the passage of river traffic. Commissioned by main contractor Skanska and M&E consultants High-Point Rendel, DavyMarkham was responsible for the 13 tonne motor-driven slew ring assembly, which provides rotation, while Cleveland Bridge undertook the fixed bridge structure. In addition, DavyMarkham designed all the mechanical, hydraulic and electrical systems that perform the opening/closing functions, as well as the PLC control architecture, traffic barriers and signals, and CCTV river, road and bank observation system.

Its emerging reputation as a specialist bridge engineering contractor latterly helped DavyMarkham gain the contract for restoring Hull’s historic Wellington Street swing bridge to fully working order, under the direction of Hull City Council and consultants Pell Frischmann. In addition to reengineering the centre pintle support structures and slew bearing mechanisms, on which the two independent bridge leaves rotate, it is also retrofitting inverter-controlled electric motor/gearbox units and a PLC-based control system. As is typical on moving bridge contracts, it will also install rising barriers, wig-way signals and PA systems for controlling bridge and waterway traffic.

In addition to applying its engineering skills and dedicated computer systems to bridge projects, DavyMarkham can bring to bear much the same rotational and lateral movement techniques to sliding roofs, retractable stadium track and seating sections, rotating boat lifts, flood defence systems like the Thames Barrier and other movable structures. Not only that, it additionally provides routine maintenance, including visual inspections, mechanical checks and hydraulic/electrical tests, to ensure its engineered structures deliver the required design life.

Further enquiries to DavyMarkham, Prince of Wales Road, Sheffield S9 4EX, telephone 0114 244 9971, email