Client: Armec - Tarmac JV
Work on the Bollin Tunnel – one of a pair of tunnels on the second runway development at Manchester Airport – was completed on time, thanks to sophisticated travelling 1000kN Megashor formwork and falsework designed and supplied by RMD Kwikform.
The arched soffit to the 25 metre wide and 260 metre long single span parabolic in-situ concrete arch was supported on three 15 metre high RMD Kwikform Megashor towers that travelled the length of the tunnel as construction proceeds. The towers were mounted on skates located in running tracks either side of the tunnel. After each pour was complete the towers were hydraulically jacked up and repositioned further along the running track in readiness for the next concrete pour.
While the vast majority of the RMD Kwikform components were standard items, the ring beams were specially manufactured to the tunnel's curvature. However, the complexity of the design was such that the RMD Kwikform solution also utilised the company's Rapidshor falsework system, Alform and Alsec beams and a host of accessories.
RMD Kwikform was involved at the earliest design stage and the contractors – a joint venture between AMEC and Tarmac – chose the RMD Kwikform solution because the use of proven standard systems and components resulted in what it described as “a very efficient and competitive design”. The contractor's Structural Agent, Tom Smith, has gone on record as saying that; “ RMD Kwikform has supported the project every step of the way from the earliest design stages, through site trials to site assembly and erection, with consistently prompt delivery in line with the tight construction programme.”
The tunnel, which is located midway along the 3km long runway, is used to divert a section of the River Bollin. It includes an access track on each side for maintenance and a public footpath along one side.
Megashor is fast becoming established internationally for its high load capacity and modular flexibility. On the other side of the world from Manchester Airport it was used in the construction of the 295-metre clear-span steel truss arches at the Sydney Olympic Stadium. It was also used at the South Arne Project at Nigg in Scotland.