Works along a stretch of twin tunnels on the Circle Line (CCL) - between Paya Lebar and Stadium MRT stations - have reached nearly 50 per cent completion since tunnel strengthening works began on Jan 17.The works, which necessitated the partial closure of tunnels during normal operating hours, is due to an issue known as tunnel squatting.This refers to the phenomena that occurs when underground tunnels built in soft soil such as marine clay become deformed when the soft soil above compresses. Parts of the said train network are in soft marine clay.Robotic arm gives works a lift AsiaOne was among the media invited to witness part of the works along a stretch of tunnel between Dakota and Paya Lebar MRT stations, where a robotic arm was working on the last of 152 inner bound rings to be installed. Read more