Hong Kong’s embattled rail operator on Thursday dismissed public safety concerns after it emerged that more than 20 areas around its To Kwa Wan station building site had been sinking since construction began six years ago.MTR Corporation managing director Jacob Kam Chak-pui said the land subsidence related to its scandal-plagued Sha Tin-Central Link, the city’s most expensive rail project, was “a common phenomenon” resulting from piling, excavation and ground water extraction work.“Things have stabilised, with minor fluctuations in recent periods,” Kam said at a press briefing to announce the firm’s interim results.He was responding to media reports citing internal MTR documents in 2016 indicating that 23 residential buildings around the station were sinking beyond acceptable limits.Buildings Department’ guidelines say action must be taken if there is land subsidence of more than 2.5 cm.According to the reports, BMW House near the new station had sunk by 6.3 cm by 2016.