KCRC confirms error caused cave-in and resumes tunnelling
The cave-in of a road in Tsim Sha Tsui on Sunday was the result of a miscalculation of soil conditions during tunnelling 20 metres below, the Kowloon-Canton Railway Corporation admitted yesterday.
But the corporation insisted that continuing the work would help to stabilise the soil and that stopping the boring machine now would do more harm than good.
The slow lane of Salisbury Road was still closed yesterday at the scene of the cave-in, which damaged a storm drain and a gas pipe when it occurred early on Sunday morning.
The KCRC spokeswoman said the subsidence was caused by a change in soil conditions that had not been anticipated.
'As the machine moves forward, it creates a tunnel ring at the rear end of the machine to fill up the void and support the soil, so stopping the machine at this moment would do more harm than good,' she said.
But civil engineering expert Greg Wong Chak-yan said the void created at the head of the tunnel, especially in soft soil, was dangerous and 'the KCRC should proceed slowly to minimise the scale of the subsidence if one occurs'.
Yau Tsim Mong district councillor Henry Chan Man-yu said the KCRC should conduct a full assessment before resuming the work.
Legislative Council transport panel chairman Andrew Cheng Kar-foo said he 'dare not' ask the KCRC to halt the project, as 'they should know best the risk they face'.
It was the second interruption in eight months involving the 3.8km southern extension to link the East Rail and West Rail lines. The previous one created a hole three metres deep and delayed work for three weeks.
The tunnel is 100 metres short of a link-up with the East Rail line at Tsim Sha Tsui East. The project is due for completion in 2009.