Tests under way for use of rubberised geo materials in the construction of the 3.2 km long elevated corridor on Anna Salai

Tests are underway for the use of rubberised geo-grids, geo- cells and geo-synthetics in the construction of the 3.2 km long elevated corridor from Saidapet to Teynampet in stretches running over the Chennai Metrorail tunnel at a cost of ₹621 crore.

M-sand is being filled inside geo-grids and geo-cells and compacted using water at 50 plus locations to strengthen the soil over the tunnel. Minister for Highways E. V. Velu who inspected the project site on Sunday, urged the contractor to speed up the work.

He said that the soil strengthening had been tested and approved by IIT Bombay’s soil mechanics department. This was the first time that a structure was coming up over an underground tunnel, he said.

Sources in the Highways Department explained that the 14-mt wide corridor is being constructed in three stretches – 655 mts that do not have the tunnel below where pile foundations are being constructed at 22 locations; for a length of 1955 mts 69 micropiles are being constructed and in 460 mts at Teynampet and Nandanam Metro stations provision has been made for portal frames.

Instead of concrete columns that tend to be quite heavy, steel columns are being used in the construction of the corridor for which Chief Minister M. K. Stalin laid the foundation in January 2024. “These would be pre-fabricated and help in speedy construction and reduce weight of the structure. The weight of steel would be 2/3rd of concrete. Though the cost would be 20% more than concrete,” explained another source.

Upon completion, the corridor will allow motorists to cross seven traffic junctions at Eldams Road, SIET College, Cenotaph Road, Nandanam, CIT Nagar Third and First Main Roads, and Todd Hunter Nagar-Jones Road on the busy arterial road, which is used by around 2.37 lakh motorists every day. The work is being carried out through engineering procurement construction mode of contract.

Senior officials including Secretary Highways R. Selvaraj, Chief Engineer (Construction and Maintenance wing), Sathyaprakash, Special Technical Officer R. Chandrasekar, Superintending Engineer M. Selvakumar, and Divisional Engineer (C&M wing), Chandrasekar were present during the inspection.