Q&A: Andy Thompson, Vice President, Hatch Mott MacDonald
Andy Thompson, Vice President at Hatch Mott MacDonald, talks to Rhiannon Garth Jones about travelling the world in the tunnelling industry.
Andy Thompson graduated from Newcastle University’s Mining Department in 1986, and followed what was then a fairly regular path to South Africa. After a couple of years working for AngloAmerican, he moved to Mott Hay and Anderson (now Mott MacDonald) where he worked on several projects, including the Channel Tunnel. He has worked at the firm for 26 years, of which the last 10 have been with Hatch Mott MacDonald, the company’s North American joint venture. During that time he has also obtained an MSc in Construction Management from the University of Bath, UK.
What do you think have been the most influential technology advances during your time in the tunnelling industry?
There has been an improvement in the materials that we have at our disposal and the uses to which they are put. For instance, the steel that we use in the cutters is much stronger and more durable than it was 25 years ago. Another example would be developments in segmental lining gasket technology. These days we use honeycomb HDPE gaskets, so that when they are compressed they squash sufficiently to create the watertight seal we are looking for. When you compare the range of gaskets available now, as well as the water pressures they are able to withstand, with what was available 20 years ago the difference is significant. The other thing, of course, is how significantly data acquisition and management has changed. The ability to understand what is happening in real-time, the sensors on the tunnelling machines, and the fact that you can have all your instrumentation linked mean that a lot of the unknowns have become better understood. The industry’s use of that kind of technology has made managing projects and understanding what’s happening much easier. You can identify trends and head things off before they start.
Are there any technologies currently in development that you think might improve things further?
High-pressure water jetting to help cut rock could make improvements. It can certainly reduce the wear on cutting tools, whether it’s a tunnel boring machine (TBM) or a drilling machine. There are a lot of changes in a lot of different areas at the moment, that taken together are making a difference. But I don’t see one big thing. I could be wrong, of course. There’s a lot of emphasis on the commercial and contractual elements of tunnelling, and about the right way to deliver projects – there are a lot of options, because different jurisdictions require different approaches. In terms of technology itself, I think people have ways of using technology creatively, which might bring about change – but nothing earth-shattering right now.
When you graduated, did you envisage yourself working on the massive tunnelling projects you’ve mentioned?
No. I always thought that mining engineering would allow me to go overseas, but I never imagined the career I would have. It has been very interesting, but I’ve never really worried about or pushed for the next project, or expected to live in some of the places I have, because, traditionally, British companies just didn’t work there. During the recession in the 1980s, Britain wasn’t the most attractive place for work, so I went overseas. When people say that there’s no work out there now I think, ‘There is, you just have to travel for it’. I’ve had a very interesting and varied career because I’ve been prepared to move.
How do the large-scale projects in the USA compare to other places you’ve worked?
I would say the major difference is in the procurement approach that is adopted and how the funding source of a project can impact various issues. Having said that, procurement models vary wherever and whomever you work for as a result of legal framework and other client preferences/requirements. Understanding the constraints within which you have to work and being flexible and open-minded to the differences and challenges this brings has been a continuous learning experience. One specific example related to the USA would be the Buy America requirements that we are obliged to work with on the East Side Access Project as a result of the Federal funding we receive. From a construction viewpoint there is not a significant difference as the tunnelling industry is a global industry and so the tools, equipment and methods we use in the USA would, for the most part, be familiar to tunnellers in other parts of the world.
Would you recommend the tunnelling industry to mining engineering graduates?
Yes, although the skills are not directly transferable, or at least they weren’t when I graduated. For example if you wanted to do structural design, you would have to learn that element, but the management and production environment certainly is. Crosspollination is always a good thing and you should always be learning new skills. If you think you know something entirely, then you’re tired, because that should never be the case. Also, there’s more and more tunnelling work to be done as cities get bigger and bigger, and the only way to go is underground. Those big UK projects haven’t stopped coming since the Channel Tunnel – there was the Jubilee line and now Crossrail. There’s plenty of work and a shortage of engineers wherever you look. Personally, I think it’s a very exciting and interesting industry to be working in at the moment as the challenges that are being presented require innovative, creative and technically rigorous, but safe, solutions.
Andy Thompson employment timeline
My first site project in the UK was settlement monitoring and general oversight of the Earl Storm Relief sewer in South Bermondsey. This sewer line was part of the redevelopment of the Bricklayers Arms’ goods depot into housing in the late 1980s and passed underneath the main railway line out of London Bridge.
My next project was working as Assistant Resident Engineer on the A20 Round Hill tunnels. These were the first road tunnels to be constructed in the UK using sequential excavation and sprayed concrete initial support, with a cast in place permanent lining installed afterwards.
Immediately after that I went out to Denmark, to work on the Storebaelt project. The company was there to oversee the construction of the project, which is probably still the most challenging soft ground tunnel that’s been built and resulted in some unique solutions. One well-documented solution was the so-called Project Moses. In an effort to reduce groundwater pressures ahead of the TBMs, 49 deep wells were drilled up to 70m below the seabed from jack up barges. Once completed, with the pumps installed, this had the effect of reducing the groundwater pressures by some three to four bar, enabling us to undertake compressed air interventions into the TBM cutter heads at realistic pressures. This solution was also used for the cross passage excavation that followed behind the TBM mining, and was performed using hand excavation through the glacial till and marl. In those cases we had to ensure complete stability and control of the groundwater before mining started, and the dewatering was used in conjunction with ground freezing and grouting to achieve this goal. We also had to overcome the challenges posed by the flooding that occurred to two of the TBMs as well as a fire on one of them. Lessons were learned regarding the performance of concrete during fires and importantly revisions to mixes and the use of polypropylene fibres to enhance fire resistance, something that is pretty much standard in tunnel designs these days. This project also kindled an interest in the management of risk in underground works that remains with me to this day.
I went to Hong Kong for six years to work as Resident Engineer on what was then known as the Strategic Sewage Disposal Scheme, now the Harbour Area Treatment Scheme. That project was 32km of hard rock tunnels, 10 pipes, and treatment upgrades, all underwater in the harbour.
Then I moved to Turkey to work on the Greater Istanbul Water Supply project, which was an approximately 160km water supply project to bring water from the Asian side of the Bosphorus and carry it underneath to the European side, where it could be treated. The idea was to meet the city’s water need for the next 40 years, which was a particular problem because it was growing by about a million people a year. This project, the first tunnel crossing of the Bosphorus, included a downhill 7.5% TBM drive to get under the Bosphorus channel.
In 2004, I moved to the USA and have been there ever since. I have worked in Atlanta, Georgia, on the West Area CSO project, which was 13km of hard rock tunnels, 8m in diameter, to store up to 177 million gallons of combined sewer overflow.
Next I was involved with the Edison Force Main project in New Jersey. This project was to replace an existing force main beneath the Raritan River through extremely poor ground conditions with very limited cover to the river bed. To achieve this, we used precast concrete segmental linings with an earth pressure balance TBM, a first for New Jersey, and installed two pipes through the tunnel.
I’ve been working on East Side Access, in New York City, since 2006, which is like the US version of Crossrail. I started off putting the contract packages together and now I manage all the heavy civil construction on the project, reporting to the Senior Program Executive. It’s costing US$9.3bln and is scheduled to be finished by 2020. We’re excavating huge station caverns underneath the existing Grand Central Station in the heart of Manhattan using drill and blast and hard rock TBMs. Over in Queens, we have built 3km of tunnel using slurry TBMs, a first in New York and only the fifth use of such technology in the USA, beneath the busiest railroad interlocking in the country, handling 800 trains a day. This has been achieved through poor ground, with limited cover and with no disruption to the train service. The project is still the largest infrastructure project in the USA that the federal government is investing into. All the excavation is complete and we are now moving into the facility creation part of the project, turning the tunnels, or new real estate, into the finished railroad facility.