How much of our railway network would exist if its Victorian pioneers had been obliged to engage with focus groups and ponderous consultation processes? Even Parliamentary scepticism did not greatly impede Brunel’s progress with his 118-mile ‘billiard table’ – the Great Western Main Line from London to Bristol – which went from promotion to approval to completion in just eight years. The first phase of HS2 – albeit 22 miles longer – will take 16. We just don’t get on with things any more. There’s a whole load of interwoven reasons for this, from our institutional fear of failure to Mr & Mrs Nimby’s loud voices and the now-ubiquitous Great Crested Newt. They all act to elongate timescales.

But what if there’s an obstacle threatening to derail your project – not years away, but weeks? What if there’s nothing in the toolbox that will quite do the job in the time available? You don’t want a talking shop or an options study; what you need is a way forward… today. What you need is Chris Scott and his prowess with steel and hydraulics.

Coalface teaching

I find Chris on the first floor of an innocuous office building, overlooking his workshops on the former site of Barnsley Main Colliery. The desk he’s sat at is as characterful as he is, crafted from pine (the desk, not Chris) and probably salvaged from one of the many pit offices he’s occupied over the years. Scattered across it is a collection of sketches and hand-written notes. Retirement age came and went some time ago without Chris noticing. Whilst his brain remains sharp – and it does seem frighteningly so – there’s no chance of him giving up. He’s got the best job in the world, he reckons: people with problems knock on the door and he doesn’t go to sleep – almost literally – until he’s solved them, theoretically at least. How satisfying is that? Just ask Tesco about the doughnut machines he built for them.

Chris provides something of a counterpoint to a society besotted with qualifications, one which has now created a market for graduates at McDonalds. With no O-levels, he walked away from school at 15 to join the Coal Board as its second-youngest entrant. Ironically, they made him go to college for nine years – “the long ChrisScott-021 [online]route” he calls it – studying to become an accomplished mechanical engineer. To that end, he won top prize every year. He left mining after the turmoil of the 1980s, moving to a small steel fabrication firm, Foulstone Forge, which he eventually acquired. Today he’s also a co-director of ISS (Innovative Support Systems) which manufactures a number of rail-facing products. No- one could suggest he hasn’t done alright for himself.

But it would be wrong to give the impression that Chris ploughs a lonely furrow as an innovator. Whilst he is clearly self-motivated – always eager to get his head around the next conundrum – he actually sits at one point of a triumvirate: developing, testing and implementing solutions in collaboration with Colin Sims, a principal engineer within Network Rail who is challenged with resolving many of the problems thrown up by tunnels, and Keith John, AMCO Rail’s senior contracts manager, with whom Chris has a long- standing relationship. AMCO has offered great support over the years – moral, practical and financial – and continues to do so as new ventures emerge.

Tunnel vision

With their mining background, it’s no surprise that many of those ventures have applications underground. Back in 2004, AMCO’s work relining Strood and Higham tunnels benefited significantly from Chris’ handiwork: mobile crash decks, protective workforce shelters and a 10-tonne bogie for transporting materials that ran along the six-foot. More recently, his manipulator and “leg-spreader” coaxed 87 girders into place during the partial rebuilding of Holme Tunnel (see issues 109 and 113 of Rail Engineer), each of them weighing about four tonnes.

That was all bespoke kit – built for a purpose, then dismantled for recycling. Probably his best known off- the-shelf product is RamArch, a support system used for shotcrete reinforcement, comprising curved panels of wire mesh that are bolted together to form an arch.

Each provides a one-metre advance. In 2011, it was installed in Devon’s Whiteball Tunnel to address a rapid deterioration of the brick lining over a distance of 388 yards (see issue 80 of Rail Engineer), about one third of the tunnel’s length.

RamArch itself is quick to assemble; the tougher test from a time perspective comes with the design requirement to secure additional resin-bonded pins in the lining as extra fixings for the shotcrete. At Whiteball, where a possession had been booked for the last Christmas period, this involved drilling more than 6,200 holes into the brickwork at the crown. However, using manual techniques, the need to apply an upwards force of 38kg when drilling each hole was immediately deemed unsustainable in practical terms.

Instead Chris built an elevating platform – christened the “four-poster bed” – and arm onto which Hilti TE76 combihammers were mounted on spears at 750mm centres. The pivot point of the arm could be pushed outwards to reach the tunnel’s centreline and the whole thing then raised to its required working height. Both the positioning and the drilling operation were hydraulically driven and controlled from a panel on the platform. The machinery typically completed an array of six 300mm- deep holes in less than a minute, the TE76s proving remarkably resilient.

Whilst the above might seem a rather mundane task to focus on, it is illustrative of the high-volume activities the railway will need to transform in delivery terms – through technology or mechanisation – if it is to meet its future network availability targets.

The next step for Whiteball will be to shotcrete the haunches; a 4-metre wide strip at the crown having been completed over Christmas. Doing that without significantly disrupting services is a headache now focusing the minds of those involved. Chris has a solution which, if adopted, could change the way minor works are undertaken in tunnels long term. More than that we can’t currently say.

Milford-117(mod) [online]

Milford-131 [online]

As for RamArch, it now has two siblings: Aspin RamPad, a simple, lightweight foundation system for structures such as signal posts that obviates the need for wet trades, and RamWall, comprising layers of steel mesh which can be built up and filled with stone to form retaining walls of almost any size and shape. This has recently been used to replace a section of failing revetment protecting the Cambrian coast line from sea erosion at Tonfanau. It also forms the walls of a vertically-sided embankment on Scotland’s Kintyre peninsula where access was needed over a gully to move a 130-tonne transformer. Eye-catching stuff.

Looking for trouble

For many decades, hard-working steam locomotives belched a wealth of unpleasantness from their chimneys, helping to destroy the ozone layer and create thousands of jobs in ‘green’ industries. “Every cloud…” and all that. Although air quality has improved hugely since their demise in the Sixties, they have left a maintenance legacy: the coating of soot on many tunnel linings. Historically, engineers have had to accept this as a fact of life, but the recent onset of electrification work has – amongst other drivers – brought into focus a need to expose the brickwork in order to obtain a clearer understanding of its condition prior to the fitment of overhead line equipment.

For small-scale repointing or repairs, soot accumulations are removed – very laboriously – by the workforce using scrapers and wire brushes; air and water jetting has also been employed. However, due to the inefficiencies involved, wholesale treatment of tunnels by either method would be unrealistic, even if
you could properly mitigate the health and environmental risks they both pose. So it would have been tempting just to bury this issue in the too-difficult pile and hope it was soon forgotten, but, to its credit, Network Rail is tackling it with some vigour. Already doing its business in the East Midlands is Chris’ latest creation – his patented soot scabbler.

Clean sweep

In principle, the machine is not desperately complicated – it has just two main components: a vacuum unit linked by hose to a scabbling head. What’s difficult with such systems is getting the detail right as this determines their ultimate effectiveness.ChiswickPark(2) [online]

Weighing 850kg, the scabbling head is held at the back by a road-rail vehicle and offered up to the intrados. Inside it are 15 wire brushes, comprising 450mm lengths of haulage rope; these are inserted through holes in a solid steel  shaft, arranged helically to prevent any impulse loading of the brickwork as they rotate, as well as reducing vibrations due to cyclical harmonics. When they’re worn out, changing one brush takes about five minutes.

The head runs on four, small bearing-off wheels, mounted on sliders which the operator adjusts to provide the optimum interaction between brushes and soot, but the least possible impact with the brickwork itself. Around the head is a gap of 30mm – surrounded by a polyurethane skirt – allowing air to be drawn in at a rate of 15.7m/s. With the brushes rotating at around 200rpm, this configuration prevents anything from escaping, even though the soot gets pulverised almost to dust. “We’re touching on particle physics now”, remarks Chris with a twinkle. The RRV travels slowly through the tunnel, cleaning a longitudinal band 760mm wide. If the head was any larger, the load created by the suction would be sufficient to dislodge any delaminated brickwork. To ensure an even loading over small changes in profile, sliders and springs allow the front of the head to ride the undulations whilst the rest of it is held steady by the roadrailer. The soot is pulled through the 300mm hose into the suction plant where it is deposited directly into 600-gauge visqueen bags inside building sacks. Although the soot is non-toxic, it’s reassuring that the workforce never comes into contact with it.

What we have here is a vacuum cleaner on an industrial scale. As you might expect, development has involved some trial and error in order to get the hardware and operating methodology right. Trials were undertaken in a disused tunnel at Alfreton as well as the Old Dalby test track. What’s emerged onto the network since then is a machine that meets everyone’s best expectations.

Out of the box

In the great scheme of things, those of us who make a living by scattering words about only leave footprints in the sand. Our efforts are transient: you will have forgotten this article tomorrow, even if you’ve stuck with it to the end. But that’s not the case with everyone. In a world besotted with fluff and trivia, it’s reassuring to know there is still a place for muddy-booted folk whose big footprints are set in concrete. Not wishing to overdo it (and I can sense my editor pulling his hair out), they keep the Brunelian spirit alive. With the railway under increasing scrutiny and pressure to reform, it needs pioneers now more than it ever has.

Photos courtesy of Four by Three.