To overcome it, the highways department has planned to take up ground improvement using prefabricated vertical drain in the main work of forming link road and construction of the bridge. 

“During ground preparation for road construction, difficulties were encountered due to soft ground, which included sunken machinery. On further soil exploration by digging the existing ground with the excavator the subsoil condition is found to be soft and loose watery clay mixed with sand and decided to get proper soil investigation before embankment formation,” said highway department officials. 

The highways department got an expert opinion from Anna University, Geotechnical division and their report confirmed the necessity for soil stabilization. “Considering the prevailing soil conditions at the site the most suitable ground improvement methods recommended by Anna University are removal and replacement of soil, pre-loading with vertical drains and installation of stone columns. The method of pre-loading with vertical drains is found to be cost-effective and ideal for existing site conditions,” the officials said. The highways department also got a second opinion from the Geo-Technical Engineering Division, IIT Madras and also to get proof checking of PVD design. 

“We have invited bids for the ground improvement using a prefabricated vertical drain,” the official said, adding that once the improvement works are completed, the link road and bridge construction work would be taken up. 

The highways department has proposed a link road from OMR-Pallavaram Radial road junction passing through Okkiyam Thoraipakkam crossing Buckingham Canal and connecting ECR road at Neelankarai. The link road project envisages direct connectivity from OMR and to the ECR area to improve connectivity in the entire south-western part of the city. The link road project was proposed in 2014 at a cost of Rs 204 crore. Based on the land acquisition and design change, the project cost was revised upward to Rs 192 crore.