03 August 2017
When In A Hole – Keep Digging
HS2 will revive British tunnelling
by J.R. Thomas
Last week we looked at HS2 and what it may do, or may not do, for some of Britain’s regional cities. Preparation work has been under way for a couple of years with construction teams being assembled, tenders sent out and returned, and most depressingly for those who live only too close to the new line north-west of London all the way to Birmingham, blight notices sent out. They are not called blight notices of course; they are warnings of compulsory purchase, for the lucky ones.
The lucky ones indeed. At least they know that at some time fairly soon their agony of uncertainty will be ended, the cheque will arrive for their house, and they can move to some new home. The less lucky ones will have been told they are on a possible route (mostly north of Birmingham or near proposed buildings for the railway) and that their homes might be required. The least lucky of all are close to the railway but not eligible for being bought out. For them, years of irritation await; the great earthmoving machinery will soon arrive across the fields or at the end of their lanes and the works will begin. When that ends there will be a very brief pause whilst everything is wired up and tested; then the trains will begin to screech past, day and night. The HS2 project directors say that the line is carefully designed to minimise noise and that screening will be put in place where necessary, but that has not stopped those living close to the route continue their campaigning against it, or at least for as much as possible of the line to be in tunnels.
The protestors have had some success with this, though the rule of thumb would appear to be that the closer to London the line is, the more likely it is to be in a tunnel. This does not always mean that whatever is sitting above the tunnel will be saved. More than 100,000 people are potentially at risk of being disturbed by tunnelling underneath them – though oddly enough, most of them are not complaining at all. That is mainly because they are dead. HS2 will mean the removal of the burial ground at St James’s Gardens which is estimated to contain about 40,000 sets of human remains, to build a new Euston station entrance. It will also pass under part of Kensal Green Cemetery, which has around 60,000 sets of remains in it, though the line should be deep enough to avoid the necessity of any exhumation. This will be a relief to at least one resident – Isambard Kingdom Brunel, pre-eminent Victorian railway builder and builder of Box Tunnel in Wiltshire who would perhaps not be amused by the irony of being removed for a new railway. His father, in the same plot, builder of the first Thames Tunnel which ruined his health, might though see this as divine providence at work.
The Victorians were great tunnellers. The Brunels are the best known, but the greatest of all was James Henry Greathead, a South African. He came to London at the age of twenty, trained as an engineer and specialised in tunnelling matters. His first employment was for the Midland Railway but he was soon working on a second tunnel under the Thames, which proved a great deal easier to construct than Brunel’s had done, partly due to many of Greathead’s inventions, the most notable being one still in use today, the hydraulic jacking systems of edging the tunnel cutter forward inside its shield. He also pioneered the use of compressed air in tunnelling machinery and soon made himself the expert of choice for any Victorian entrepreneur contemplating diving underground. Though that was mostly for railway reasons – much of the initial system of the London Underground railway was built under Greathead’s direction or consultancy – a whole network of tunnels for sewage and water was also built around this time; and even a carriage tunnel, still in use, the Blackwall Tunnel.
If the Victorians were great tunnel innovators, by the time of First World War the era of British deep digging seemed to have largely gone. It was the Swiss who, not surprisingly, became the great innovators in digging deep down, though the New York subway builders were quick learners too. Britain really only got back to the cutting edge techniques of tunnelling, a couple of new tube lines and the Newcastle Metro withstanding, in the late twentieth century with the Channel Tunnel. That was followed by some road tunnels, the complex Heathrow Express extension which suffered a partial collapse, and then the very complicated Cross Rail (not yet better known as the “Elizabeth Line”) tunnel across, or rather, under London. HS2, and if they happen, its northern extensions, should further develop our national ability as tunnellers, involving a great variety of below ground conditions and above ground sensitivities. With all due credit to the Swiss, it is one thing to hew through solid rock; unknown water and the danger that the two ends won’t meet in the middle are the main risks of that. But to dig out of central London, under the Chiltern Hills and then through bits of rural England and under the suburbs of various cities is a challenge indeed. Clay, rock, sand, water, unexploded bombs, old mine workings under the ground; sensitive residential buildings and sensitive residents, industrial buildings and processes, offices with deep, or even worse, not deep enough foundations, above (to say nothing of overcrowded cemeteries).
Our famous business heroes now are men and women who work in the virtual world; the Buffets and Gates and Bezos of this world, the disrupters of trading patterns, not the disrupters of earth. Tunnel engineers are like the moles they emulate; a shy lot, no names, no bragging rights. But leaders of their profession will soon be working cautiously on one of the most difficult and sensitive projects of all time. And at the end of it, as the trains scurry back and forth, they will be forgotten.
Brunel is admittedly not forgotten. He died aged 53, exhausted. His memorials are not so much his tunnels, as the soaring roofs of Paddington Station, the billiard table flat Great Western Railway, and his Great Eastern steam ship, the largest built at that time. He ensured immortality by posing in front of its anchor chain with a massive cigar, giving the abiding image by which he is so widely known. Greathead was also felled by a heavy workload, dying at the age of 52. He was pretty much completely forgotten for a century even though so many of us travel through his works every day. In the 1990’s, complex rebuilding works at Bank tube station in the City necessitated a new air vent to be placed in front of the Royal Exchange. To disguise what it was, somebody thought of crowning it, ninety eight years after his death, with a statue of he who had done so much of the tunnelling underneath. So there stands James Henry Greathead, with hot air constantly blowing up his trouser legs. It’s one way of achieving immortality.
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