Settlement at Upper Changi

While caves in are rare occurrence during the tunnelling phase, they do happen. Every TBM that launches is accompanied by a watchmen which is station on the surface within a safe distance of the cutterhead location to monitor and phone back to the control room any depressions should they appear. In the inevitable situation where a passing vehicle gets timed with the sinkhole, it gets carried in with the ground. Quoting a press release by the LTA earlier today, "At about 8.30am on 24 April, a depression appeared at the centre lane of Upper Changi Road East (in direction towards Expo). A tipper truck that was passing tilted into the hole."

Photo credit - @Andre_Giam

Cave in near apartment 704 of Changi Court

Though the sinkhole's location is near the Upper Changi station site, the tunnelling works north of the station are carried out by its sister contract C923A. A good gauge of progress as the 2 TBMs from the PIE shaft is nearing the end of its final drive. I presume the authority and STEC would conduct stringent soil improvement works at the area before resuming activities at the cutterhead.