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When Larsen and Toubro, one of India’s leading construction contractors, was awarded contracts to build most of the new 29-kilometre Dwarka Expressway from Mahipalpur in Delhi to Kheri Dhaula via Gurugram, they did not have to look far to find a reliable supply partner for the bearings required by the motorway’s bridge structures. Having worked together on recent landmark projects such as ITC One Colombo, the Statue of Unity and the Mumbai Trans Harbour Link – as well as earlier projects such as the Sahar Elevated Access Road and Hyderabad Metro Railway – the contractor knew what it means to work with mageba. For one thing, mageba always tries to be more than just a supplier where key components such as bearings and expansion joints are required for bridges and buildings; we are also glad to contribute our expertise in this specialist niche of the construction industry where we see an opportunity to optimise the structure’s construction.
The expressway’s numerous bridge structures, including an eight-lane flyover of length 8.5 km, needed a huge number of bearings to support their superstructures while allowing movements and rotations as required by their designs. These bearings were originally specified to be of the spherical type, and with so many required, the costs of design, supply and installation would be very substantial. As an alternative, mageba proposed the use of elastomeric bearings – appropriately designed to deal with the significant horizontal forces arising by means of seismic isolation. This change enabled the design and dimensions of the substructure at many bearing locations to be optimised, and reduced the bearing supply and installation costs, while also adding a degree of seismic isolation to better protect the structures in case of any earthquake. The bearing supply costs were further reduced by proposing the use of locally supplied natural rubber rather than imported chloroprene rubber to manufacture the bearings.
Supply and installation of the bearings is currently ongoing. The 736 LASTO®BLOCK elastomeric bearings were designed with diameters of up to 1100 mm, to support loads of up to 17,294 kN and resist horizontal forces of up to 1036 kN, while the 160 RESTON®SPHERICAL bearings and five large RESTON®POT bearings can carry loads of up to 2750 kN and 16,400 kN respectively. But it is not the way these bearings were designed and manufactured that will be remembered most about mageba’s contribution to this project, but our local team’s initial inputs in proposing a bearing solution that offered several significant advantages to the project as whole. The kind of added value that we like to make part of our everyday work, wherever possible.
Bridge designer: L&T Infrastructure Engineering Ltd.
Contractor: Larsen & Toubro Limited, Construction
Owner: National Highways Authority of India