An independent investigation is being carried out into the collapse of a section of the US$752M Lane Cover road tunnel in Sydney (T&TI November 2004, p25), which the contracting joint venture of Thiess and John Holland, blamed on an “unforeseen geological event”.
The collapse, on 2 November, left one apartment building hanging over a 10m wide, 10m deep hole, and emergency services evacuated residents from another nearby building. No injuries were reported.
The probe, by Professor Ted Brown, an expert in rock mechanics, started on 7 November. An official government investigation, though the WorkCover agency, is also underway.
Thiess and John Holland are both controlled by Leighton Holdings, Australia’s largest contractor. In a statement Leighton Holdings said: “The subsidence occurred following an unforeseen geological event, which is currently being investigated. Workers in the tunnel were evacuated and all are accounted for.”
Thiess-John Holland have infilled the affected area with concrete, but have yet to decide whether to continue the excavation of the exit ramp or move it to another location. Leighton Holdings said, “the incident is not expected to affect the tunnel’s construction programme and it remains on track for completion” in 2007.
The tunnel section, close to a planned exit ramp, was being excavated by roadheaders at the time of the collapse, which occurred in the Longueville Road-Epping Road area of the project. About 60 people were evacuated from their homes. The tunnel contractors have since agreed to buy the apartments from residents who wanted to move from the two worst affected blocks.
Tunnel contractor’s spokesman, David Saxelby said: “If owners want to sell, we will pay them what their apartments were worth before the incident. Naturally, there will be independent valuations obtained and we will pay a fair price. We will also pay transaction costs. We understand why some of the residents may not want to go back. We will help residents who want to find a new place to rent and help them financially with the move. In the meantime, we are continuing to provide residents with accommodation in serviced apartments and with other support.”
Work on the dual three-lane 3.6km Lane Cove tunnel started in mid-2004. Tunnelling is about 95% complete using a fleet of seven roadheaders through sandstone.
