A first-of-its-kind bridge over runway is being constructed over Adyar river at Chennai to facilitate the extension of the secondary runway to facilitate the extension of the secondary runway over it to the other side of the river. The bridge can withstand the load and landing of a long and wide aircraft like an A-380. This amazing feat is being accomplished by the Airport Authority of India.
The 200m long (across the river) and 462m wide bridge, being built by Consolidated Construction Consortium Ltd, will be completed by October this year, E P Hareendranath, the Airport Director at Chennai told TrafficInfraTech. Held by 477 pillars, the bridge will be positioned on a grid of 20m by 10m. These pillars will shoulder 2,440 pre-stressed concrete girders. The latter will be one metre high and 19.1m long and will weigh 30 tonnes each. This integrated structure will be made of piers, girders and concrete embankment so that the load of the aircraft can be evenly distributed across the bridge.
The extension of secondary runway has been awarded to KGL Constructions and Consolidated Construct-ion Consortium Ltd (CCCL). The bridge is designed by Land T Ramboll and approved by IIT, Madras. The 2,035m long secondary runway will be extended by 1400m. This will include 835m on the northern side of the river that was extended in January 2009. At present, the level of the existing secondary runway is being increased so that it can successfully be aligned with the portion that will be later extended. The bridge will have a runway, a taxiway, a side strip and service roads. A 60 metre long gantry has been erected lest the work stops owing to rains.
A hydraulic study was carried out to calculate the requirement of the future water flow and based on the report, the bank of the river was widened from 140m to 200m. Public Works Department has given the AAI a no-objection certificate for widening the banks. This will allow sufficient space for water to flow below the bridge. This will also do away with the possibility of the flooding of the runway as it had got flooded in 2005. Keeping the floods in mind, the height of the runway and the bridge has been kept a few metres above the 2005 flood level.