VIEWPOINT | TRENCHLESS & MICROTUNNELING


Above: Barbco notes benefits from guided boring PHOTO CREDIT: BARBCO


Young continues: “We do a lot for Network Rail,


for example, and there is a lot more of it, widespread around the country. They tend to be quick, small projects; I’m involved in quite a few at the moment. £2m (US$2.49m) is a typical upper budget, and that would include all the main laying of cable or piping as well as the tunneling itself and the linking up at either end.” He adds: “In one sense microbore is not very different


from large-bore tunnelling. It needs the same set of skills and standards. We still use TBMs, though smaller ones, with no onboard operators of course – though pipejacking and now directional drilling are also widely used methods. However, in some microtunnels you cannot actually enter the tunnel yourself, and that does make a big difference.” Young says: “We are doing numerous crossings for


various types of water mains, and these are within that range, 50m to 100m (54.7yd to 109.4yd). But still they take a lot of effort: a lot of time is spent preparing the shafts and putting the props in on either side of a rail track. You can be looking at a 15- to 20-week project by the time you put the access points in, one each side and set up the pipe jacks and associated works. But the actual microtunneling itself might take you four or five, maybe six shifts – and that’s it. “So small-bore needs a much greater ratio of


Above: UK perspective – Barhale PHOTO CREDIT: BARHALE 22 | Spring 2023


preparation time to tunneling time; but these tunnels are needed, and they are needed everywhere.”


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