Following numerous incidents of road cave-ins due to tunnelling work, the Chennai Metro Rail plans to set up a special committee with international consultants and professors from IIT-Madras to provide suggestions to step up safety in the city.
According to officials of Chennai Metro Rail Limited (CMRL), despite various precautionary measures being taken, there have been instances of roads caving in owing to ‘unpredictable soil conditions.’
“Even now, we do take recommendations from IIT-Madras frequently. But we want to bring in international consultants as well. This kind of a system with experts from various quarters will help us avoid such issues,” an official said.
Though there have been minor road cave-ins and cracks in buildings for a few years now, this issue gained significance when a car and a bus were caught in a huge cave-in on Anna Salai two months ago. Of the 45 km-Chennai Metro Rail stretch running through the city, 24 km are underground and the remaining 21 km are elevated. Officials claim such incidents have occurred despite various steps taken before beginning tunnelling work. Before beginning tunnelling, surveys were held on the condition of existing buildings and the number of borewells falling in the tunnelling alignment. “During these processes, we check how sensitive buildings are and the potential existing damage assessment. This is done for buildings located 50 m on either side of the tunnelling alignment. Then, during the tunnelling work, with instruments like settlement markers, we monitor if there are settlements in buildings,” he added.
‘Not just in Chennai’
Officials claim what happened in Anna Salai was a sudden collapse due to mixed soil conditions. “It’s not just in Chennai that this happens. In other cities and abroad too, many such road cave-ins have happened due to tunnelling work,” an official said.
Also, there has to be extra caution as there are many utility services running underneath like electricity and telephone cables. “It is challenging to execute this work without knowing how the utility services are placed underground. If there is a dedicated map to know how their network is, then, it would be greatly helpful while carrying out such a huge project,” he added.
