Our Insights

Tunnelling Insights from Bechtel Experts

On 3 December, the British Tunnelling Society celebrated the UK's first ever National Tunnelling Day.

Here's Steve Kay, Civil Delivery Director on the Crossrail project, talking about one of Bechtel's most complex tunnelling operations to date. #TunnelDayUK  

What makes Crossrail's tunnelling works unique? 

Really it's the scale of the project which stands it apart from anything else I've worked on. Crossrail is a complex tunnelling operation with not just long stretches of uniform tunnel, but also complex junctions, stations, ticket halls, connections between platforms, lifts and escalators. And all that is going on in-and-amongst live underground systems, and just underneath the surface of one of the busiest and oldest cities in the world.

What do you think is the best thing about the UK's tunnelling industry? 

We have some of the most exciting tunnelling in the world happening in the UK right now. Crossrail is a huge project, but we’ve also got the likes of the Thames Tideway Tunnel, the Northern Line extension and High Speed 2 in the pipeline amongst others. So there's a huge opportunity for Engineers in the UK to work on some of the best projects in the world, and for young people to learn this important craft which will see some really important milestones in London's infrastructure history. It's a unique opportunity you don't get many times in your career. 

What machinery and equipment is used on Crossrail tunnels? 

There are two principle tunnelling techniques which we use on Crossrail: boring and sprayed concrete. We use huge tunnel boring machines (TBMs) to dig out the long, uniform tunnels which the trains will pass through. These machines install segments as they go. And we use the sprayed concrete method for the more complex areas such as stations, junctions, passageways, and lift and escalator shafts. In total, the project has 42km of tunnelling.  

What are some of the major challenges you face with the Crossrail tunnelling work? 

London is one of the Western world's oldest cities and so we have to work our way carefully through a network of existing sewer lines, water and gas mains, foundations and even London Underground tunnels dating back to the 1860s. We've made some quite surprising discoveries, such as grave yards and plague pits along the way. 

Ten minutes on tunnelling with one of Bechtel's most experienced Tunnelling Engineers, Dave Shepherd, talking about his vast career in the industry. 

How long have you worked in the tunnelling industry?  

The first tunnelling job I had was in 1977 during a year out from university, at the Dinorwig underground power station in Wales. Since then, I've worked on every major tunnelling project in the UK including the Channel Tunnel, the Jubilee Line extension, the Thames Tunnel refurbishment, the Channel Tunnel rail link and Crossrail. I'm now working on some of the final elements of the Vauxhall Station refurbishment project.    

What have you seen change during your career?   

When I started out in the industry, it was very labour intensive. I've seen it progressively become more and more mechanised. I'm a tunnel Engineer and my role has also changed - it used to be more about controlling the alignment of the huge machines by traditional survey methods, whereas now it's more about managing tunnel operations and logistics, which has its own set of challenges!  

How does the UK compare to the rest of the world in tunnelling?  

The very first subaqueous tunnel was bored in the UK (the Thames Tunnel), so we have a great depth of history. And along with that we have a huge amount of skill in crafts such as timber heading. Although those skills are becoming less required with the mechanisation we're seeing, I think the expertise in this country on tunnelling is amongst the best in the world. And in terms of safety, the UK is second-to-none and it's improving with every year and every project.   

What do you predict for the future of tunnelling?   

My predictions for tunnelling are that it will continue to become more mechanised and that the need for personnel to be underground will become less and less. I recently saw an example of this type of working whilst on a project in Chile, where the machine operators were on the surface. That said, I do believe there will always be a need for human interaction.   

What has been your favourite UK tunnelling project to work on?  

Because of its high profile, it has to be the Channel Tunnel. In fact, just this Monday it was 25 years since the Service Tunnel broke through, although it seems like only yesterday. Crossrail is another favourite. It’s been great to be part of something that has such a lasting impression on the landscape of the capital. 


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