Stay Cables for Gujarat’s first Extradosed Bridge: The 3rd Narmada Bridge

In the district of Bharuch in the federal state of Gujarat in northwestern India, National Highway 8 crosses the Narmada River. The motorway is one of the country’s most important connections linking Delhi with the economic center of Mumbai and other economically important cities.

In order to provide relief from the heavy traffic congestion which often occurs in this area, the 3rd Narmada Bridge is being built. It will include 4 lanes and a pedestrian crossing and will be used together with the existing bridge that will remain in service.

The new, 1,344m long and 20.8m wide bridge consists of two 96m long side spans and eight 144m long main spans. The structure will be the first extradosed bridge in the federal state of Gujarat and will have the country’s longest spans. Each of the center spans consists of 38 3.55m long precast concrete hollow box girder segments.

At each of the pylons, there are two stay cable planes consisting of 6 stays arranged in a fan pattern that support the bridge deck. In total, DSI-BRIDGECON supplied and installed 216 27.5 - 70m long DYNA Grip® Stay Cables with a strand tonnage of 500t. 36 Type DG-P31, 36 Type DG-P37, 72 Type DG-P43 and 72 Type DG-P55 Stay Cables were used for this purpose.

The stay cables were anchored at the bridge deck using DYNA Grip® Anchorages and at the pylons using the DYNA® Link Anchor Box System. In this system, the fact that the stay cable anchorages are located outside permits slender pylon shapes because the interior of the pylon does not need to be accessible.

In addition, DYNA Force® Sensors were installed in order to permit long-term monitoring of the forces acting on the stay cables.

The 3rd Narmada Bridge is the first project in which DSI-BRIDGECON has installed the DYNA Grip® System and the DYNA® Link Anchor Box System.

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National Highway Authority of India, India