Your article is a correct interpretation of emeritus professor Ted Brown's report released by the tunnel company Thiess John Holland on 19 January.
An assessment of his findings will be presented to Lane Cove Council for consideration on 6 March, 2006.
However, as you have rightly addressed in your article, it is also the council's understanding of Professor Brown's report that the length of the rock bolts may not have been adequate for large effective spans such as those encountered at the junction of the Lane Cove Tunnel's Pacific Highway exit ramp and the air ventilation tunnel.
The report suggests that this particular junction required special design attention, and that the level of support was inadequate and unable to ensure the excavation's stability given the large effective span, low rock cover, the presence of a dyke and the poor mechanical properties of the overlying rock mass.
The council has made Professor Brown's report available from its website and is now awaiting the release of a report on the tunnel collapse from WorkCover which is due to be delivered in the coming weeks.
The tunnel collapse has been an unfortunate experience for some of our residents who had to be evacuated in the early hours. While residents of the adjoining units have been allowed to return to their units, residents from the partially collapsed building have not yet been given approval to return.
Cllr Ian Longbottom, Mayor of Lane Cove, Lane Cove Council, 48 Longueville Road, Lane Cove, 2066 NSW, Australia