Engineering Rotational Movement Into Moving Bridge Structures

Engineering rotational movement into moving bridge structures

The industrial heritage of newly renamed UK 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 success- fully 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’s 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

Civil Engineering | September 2006 27 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 t trunnions or hinge as- semblies 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 Usually constructed over busy waterways where it synchronising two sets of large hydraulic cylinders, one located on each bank of the Tyne. is impractical or prohibitive to build a fixed bridge One of the UK’s longest double-acting hydraulic cylinders, which required £20k worth of oil for the first fill, is a feature of high enough to allow river traffic to pass beneath, the high profile Great Wharf Road Lift Bridge, commissioned by Canary Wharf Contractors and again designed by Wilkinson moving or movable bridges incorporate a section of Eyre. Here, DavyMarkham undertook responsibility for the giant hydraulic ram, the hydraulic and electrical control system and as- the deck that lifts, rolls or swings aside to provide sociated support structure, under the management of Gifford & Partners and mechanical and engineering consultants Bennett & additional clearance. Generally, these bridges are Associates. The same project team was also behind the Bellmouth Passage pedestrian swing bridges, where DavyMarkham handled powered by electric motors operating winches, the complete design, manufacture and commissioning of the main bridge structures, rotating and nose-locking mechanisms, and PLC gearing or hydraulic cylinders and typically control systems. The deck structures were built to a calculated pre- camber and during construction ballast was used to compensate for incorporate traffic signals for road and water the eventual weight of the glazed passageway and superstructure, installed subsequently on site. traffic, as well as moving barriers for pedestrians One of the largest moving structures of its kind, the cable- stayed Selby Swing Bridge features a 98 m span, 1 200 t central and vehicles, which are coordinated with bridge span that rotates on a central pivot to allow the passage of river traffic. Commissioned by main contractor Skanska and M&E openings by PLC-based control systems. A moving consultants High-Point Rendel, DavyMarkham was responsible for the 13 t motor-driven slew ring assembly, which provides rotation, bridge is likely to be heavier and more complex while Cleveland Bridge undertook the fixed bridge structure. In addition, DavyMarkham designed all the mechanical, hydraulic than a fixed bridge of the same span and electrical systems that perform the opening/closing functions, as well as the PLC control architecture, traffic barriers and signals, structures, enable architectural visions to be realised in solid steel, and CCTV river, road and bank observation system. concrete and glass.’ Its emerging reputation as a specialist bridge engineering con- Usually constructed over busy waterways where it is imprac- tractor latterly helped DavyMarkham gain the contract for restoring tical or prohibitive to build a fixed bridge high enough to allow Hull’s historic Wellington Street swing bridge to fully working river traffic to pass beneath, moving or movable bridges incorpo- order, under the direction of Hull City Council and consultants rate a section of the deck that lifts, rolls or swings aside to provide Pell Frischmann. In addition to reengineering the centre pintle additional clearance. Generally, these bridges are powered by support structures and slew bearing mechanisms, on which the electric motors operating winches, gearing or hydraulic cylinders two independent bridge leaves rotate, it is also retrofitting inverter- and typically incorporate traffic signals for road and water traffic, controlled electric motor/gearbox units and a PLC-based control as well as moving barriers for pedestrians and vehicles, which are system. As is typical on moving bridge contracts, it will also install coordinated with bridge openings by PLC-based control systems. rising barriers, wig-way signals and PA systems for controlling A moving bridge is likely to be heavier and more complex than a bridge and waterway traffic. fixed bridge of the same span, due to the mechanisms involved, but In addition to applying its engineering skills and dedicated the variety of lift, swing and bascule (drawbridge) configurations computer systems to bridge projects, DavyMarkham can bring to offers architects and designers tremendous aesthetic scope. bear much the same rotational and lateral movement techniques Such creativity is epitomised by the rotating Helix Bridge, de- to sliding roofs, retractable stadium track and seating sections, ro- signed, engineered, installed and commissioned by DavyMarkham, tating boat lifts, flood defence systems like the Thames Barrier and where the overriding brief was to maintain the vision of conceptual other movable structures. Not only that, it additionally provides artist Marcus Taylor. Commissioned by consulting engineers Buro routine maintenance, including visual inspections, mechanical Happold Mace on behalf of Paddington Development Corporation, checks and hydraulic/electrical tests, to ensure its engineered it has the unusual trompe-l’œil effect of appearing to corkscrew structures deliver the required design life. across the canal. Employing perfectly synchronised lateral and rotational movement, the bridge deck travels across at 75 mm/sec, INFO while the glass/steel composite tube rotates at 3 rpm, giving one [email protected]

28 Civil Engineering | September 2006