Far below the streets of Sai Ying Pun, a huge machine is tunnelling away within a few metres of the foundations of high-rises towering above the neighbourhood.
Manned by construction workers, the machine is grinding away the rock and dirt to make way for the MTR Corp's West Island Line, which links Kennedy Town to Sheung Wan.
From 7am to 11pm the tunnel-boring machine, or TBM, advances another six to eight metres eastwards, while sensitive equipment fixed to the top of buildings above its subterranean route monitors for any ground movement.
A millimetre wobble to the left? The sensors will catch that, says MTR's construction manager David Salisbury, though nothing out of the ordinary has been detected so far.
'Can't say there's been none, because these things are so sensitive they'll record every millimetre,' Salisbury said. 'Even temperature changes within the air on a hot, hot day and a cold day will cause these buildings to move slightly.' Rather, he said, the sensors looked for 'continuous trends associated with our excavations'.
If something does happen, he and others will get an instant e-mail alert from a 24-hour automated monitoring system.
