According to the Realmillenniumists, those concerned about the lack of a true zero when Christianity dated its story, we have only just completed the first 2000 years. Of course most of the world celebrated a new epoch last year but the “true” date remains an excuse to look at the tea leaves and consider tunnelling’s future.
On balance it must be a good one.
There have been disasters of course, some of them very fresh in the mind as we reported last month and this. The dangers of fire, as tunnels get longer and also become more and more congested, is tragically underlined particularly during the last decade. Tackling fire safety, especially in transport tunnels, is top of the list.
But there have been dramatic advances in the technology and skills for creating tunnels and this still young science (despite an ancient tradition of tunnelling) has notched up huge successes during the last century. The Channel Tunnel is obviously high on the list, as are many of the big Alpine tunnels, the TransTokyo Bay crossing, the New York water tunnels, the Chicago storm drainage system and much much else. The now universal development of metro lines in major cities testifies to the importance of the industry, and so accepted is the methodology for sewers, powerlines and water supply that it does not draw comment.
Understanding of what happens during tunnelling grows rapidly. For example, as explained in our article on the Amsterdam metro, fine control of tunnelling and the application of rapidly growing systems developments means that the disruptions and impact of tunnelling, even in the most sensitive environments, can now be measured in real time and corrected, “before it happens”. Techniques like compensation grouting can allow fine working in difficult areas such as for the new tunnel beneath Harrods reported at a recent British Tunnelling Society meeting.
Soil and rock science advances mean tunnelling can be extended into hitherto impossible areas. But as the recent collapse of a NATM tunnel at Washington airport demonstrates, even several decades of accumulating experience does not rule out problems. A reason for that incident is not yet pinned down but it shows that with increasing knowledge comes an increasing need to keep the eye on the technical ball.
