INTERVIEW | KEITH BOWERS


LTC northern tunnel approach


The first of them are just in the very early


stages of operating. Obviously, our hope and our intent is that the project will then benefit from having a more skilled local community, but then afterwards it may well be that people in the community are up-skilled, to use the jargon, and then go and gain employment somewhere in the construction industry not actually directly driven by the project.


“It is an example of the way you can


use the opportunity of a big project with a big investment to generate a wider social impact. And you can argue, I think perfectly reasonably, that there’s a social responsibility to it. We are using large sums of public money so we should be trying to extract as much benefit to the community as we can.


It is very easy to


focus in on the tunnel, which is a very impressive piece of engineering, but we can’t allow ourselves to be totally fixated on digging the hole. Some of us find digging big holes quite satisfying but there is a lot of depth and breadth of other things we can achieve as part of it.” Recognising that, let us return for a


moment to the hole. It is a large one, or to be accurate, two large ones. The Lower Thames Crossing is going to be twin tunnels, 4.25km long of which 1.3km is underwater. Of the total, 4km will be TBM drives, with the balance being short cut-and-cover sections at the ends. There will be 27 cross passages, driven with a smaller TBM. The main bores are planned as a massive 15m (49ft) internal diameter, which calls for TBM size of very slightly under 16.5m. In other words the diameters will be huge. “If you go back to the early parts of


Above Heathrow Express Trial Tunnel, 1992 - early experiment to test if SCL would stick to London Clay


36 | February 2026


Above Keith Bowers installing instrumentation in the lining at Round Hill A20, c 1991


the underground system in London, they were 9ft or 10ft in diameter and were then enlarged to 12ft, which became the


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