INNOVATIVE FORMWORK FOR WINEGLASS-SHAPED BRIDGE PIERS ON A1(M)
Jun 30 2005
An innovative formwork system combining the Mammut wall formwork and pre-bent Alkus polymeric face plates in special forms designed and manufactured by MEVA of Germany have been used to build unusual wineglass-shaped concrete piers for bridges crossing the new A1 motorway. Available exclusively for hire in the UK from A-Plant Acrow, part of A-Plant Specialist Products, the Mammut/Alkus system from MEVA provides heavy duty formwork for pouring wet concrete in walls, columns, suspended slabs and many other structures. The system is being used on behalf of the Highways Agency, which is currently upgrading the A1 in Yorkshire to motorway standard.
Exceptionally difficult to build, the wineglass-shaped concrete piers were chosen to help blend in with local landmarks. They support the three overbridges being built at the new interchange at Holmfield in Yorkshire, which will provide better links and traffic flow between the existing M62 motorway and the new A1(M) motorway.
The bridges are among some 40 major new structures to be built in this £245 million project, which is the latest phase in the proposed upgrading of the A1 between London and Newcastle to motorway standard. The project will relieve congestion and improve traffic flows through West and North Yorkshire as part of a number of improvements to network management on the A1.
The work forms part of a contract won by the Design, Build, Finance and Operate (DBFO) company, Road Management Services (Darrington) Ltd that involves upgrading, maintaining and operating for the next 30 years the 53 km of the A1 running through Yorkshire between Darrington and Dishforth, on behalf of the Highways Agency. RMS is a joint venture of AMEC, Alfred McAlpine, Dragados, Kellogg Brown and Root, who are also the contractors for the project.
A total of 22 bridge piers with varying heights from 6 m and 17 m will be built, with minimal interruption to the heavy traffic flow on the M62. The piers have been built to exacting architectural requirements with a superior concrete finish. This has been ensured by the Alkus-plates on the Mammut formwork panels that use a polymeric face, providing a better quality finish to the concrete than conventional systems. The piers also have a series of vertical features, which have been produced using shaped timbers screwed to the surface of the formwork face. The same timber system was used for the features on the 7 m radius faces on the rounded ‘wineglass’ at the top of the piers.
With the Mammut/Alkus formwork system in place, the vertical stems of the piers, some as high as 11.5 m, were poured first, with the complete wineglass-shaped pier heads being made in a second pouring. Since the pier heads had different gradients the two curved head wall formwork units were set up independently at different heights for every bridge pier. KLK 230 climbing scaffolds provided both support for the formwork and also a safe working platform for site personnel.
The formwork for the piers located in the central reservation between the lanes of the M62, was erected with a special bracing design using parts readily available from A-Plant Acrow. The special bracing system meant that all available lanes of the M62 motorway were kept open to traffic during the construction of the bridge piers. In addition, the use of standard components available from the A-Plant Acrow fleet meant the formwork system was easy and fast to assemble. Overall, the contractor was extremely satisfied with the formwork systems and the concrete finish obtained.