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Channel Tunnel: a shared history

Atkins | 07 May 2014 | Comments

It’s been 20 years since HRH Queen Elizabeth II and French President François Mitterrand officially opened the Channel Tunnel, creating a permanent link between the UK and continental Europe. Since then, this remarkable feat of engineering has been widely recognised as one of the projects of the century.

More than 100 years after the first proposal was drawn up to connect the UK to continental Europe via rail, work began on an extraordinary project that would inspire engineers for generations to come. At the time, the Channel Tunnel, which links Folkestone in the south-east of England with Coquelles, Pas-de-Calais in northern France, was the most expensive construction project ever conceived. And opinion on it was divided.

“Not everyone was in favour of it,” says Martin Grant, CEO of Atkins’ Energy business, who worked on the Channel Tunnel as a young engineer. “There were people who didn’t want to create a permanent connection between England and France. They believed it threatened Great Britain’s status and security as an island nation. But it was an amazing project and there’s still something special about this iconic link between two great nations.”

The details of the design

Atkins was appointed “Maître d’Oeuvre” (independent engineering project managers) in 1980, in a joint venture with French engineering consultancy SETEC, providing supervision and project management for the design and construction of all aspects of the work. Despite the scale and obvious complexity, it took just eight years to construct (helped by the fact that there were 14,000 people involved in the design, build and financing).

According to Michael Muller, one of the directors of Atkins-SETEC and Atkins’ former managing director: “The Channel Tunnel project was perhaps the most ambitious engineering project of its time, not only in the rail sector, but from the perspective of all engineering disciplines. In working on the project, Atkins-SETEC helped both the UK and France achieve what had only been dreamt of by engineers of the past.”

The tunnel stands out as being an engineering triumph, even 20 years on. What challenges had to be overcome and how have the solutions stood the test of time?

The Channel Tunnel runs for 50km between England and France, with terminals in Folkestone and Coquelles respectively. (Image © Eurotunnel)The Channel Tunnel runs for 50km between England and France, with terminals in Folkestone and Coquelles respectively. (Image © Eurotunnel)

The tunnel is just over 50km in length, of which 37.9km is under water, making it the longest section of undersea tunnel in the world. At the time of its construction, the public believed flooding was the primary concern, but Grant points out that, for the teams working on the project, the main risk came from fire: “There was never any doubt that we could find an acceptable level of safety in terms of the fire risk but the systems for detecting and extinguishing fire, and for evacuating people, all had to be very carefully designed,” he says. “The tunnel safety system we put together was probably more ambitious in its scale and complexity than anything else that had been done before.”

This safety system is inherent in the design: the route under the English Channel consists of three tunnels – two single direction tunnels and a central service shaft. Cross passages connect the north and south tunnels to the central service area every 375 metres. This provides maintenance teams and emergency services with access to the main routes as well as giving travellers a safe area should they need to be evacuated due to an incident.

While it may not have been the main worry, flooding was still a concern: on average, the tunnel sits at a depth of 40m and, at the lowest point, it’s 75m below the surface. This created a number of challenges.

“We thought the more difficult geology was on the French side,” says Atkins’ Guy Lance, who was the project design manager for the UK tunnels. “But when we started work and moved just off the coast of England, we found that the sea bed was quite fractured and, as a result, there was a lot of water. That caused problems with the tunnel boring machine.”

New, waterproof tunnel boring machines able to support 10 bars of pressure from water infiltrations had to be designed (previously the maximum was three to four bars).

The strength and durability of the tunnel structures would be put to the test throughout its creation but, in one of many major successes, the tunnel is the only undersea tunnel in the world that is able to support, on its own, the sea bed and the weight of the sea above.

Extending the benefits

There were a number of major milestones during the construction of the Channel Tunnel but for many, this historic project is best represented by an image of French and English workmen shaking hands as the tunnelling teams broke through to meet, 22.3 km from the UK and 15.6km from France.

Martin Grant doesn’t underestimate the importance of this moment, but adds that it was a breakthrough on only one aspect of the project: “It was clearly a necessary and important milestone for those who built the tunnels but, for some people, the work had only just started at that point. The whole railway infrastructure was yet to be added, as well as the power systems and the safety systems. There was a lot more to be done.”

The Channel Tunnel provides passage to Eurotunnel Shuttles carrying cars and coaches or trucks, and also to passenger high speed trains and rail freight trains. (Image © Eurotunnel)
The Channel Tunnel provides passage to Eurotunnel Shuttles carrying cars and coaches or trucks, and also to passenger high speed trains and rail freight trains. (Image © Eurotunnel)

Lessons learned

The Channel Tunnel is connected to the high-speed railway network and motorways of the UK and continental Europe. In the 20 years it has been open, more than 325 million passengers have travelled through it. Services have expanded and now cars, lorries, caravans, motorcycles and pets can all be accommodated. It has become a vital link for leisure travel, business and trade across Europe, and has boosted economic development around the terminals through the creation of jobs and tourism.

It also continues to inspire engineers from around the world. In September 2013, Atkins and SETEC were recognised for their work on the project. The International Federation of Consulting Engineers Centenary Awards celebrated the best consulting engineering achievements of the last 100 years, which were decided by an international judging panel of industry experts. The Channel Tunnel won the Major Civil Engineering Project award.

And for those who played a part on the project, the lessons they learned continue to influence their work, on everything from new nuclear power stations to offshore oil rigs.

“The experience of seeing how a large, complex, ambitious project came together was a terrific learning experience, one that I was able to take into the rest of my career,” says Grant. “I have used the knowledge and understanding of collaborative working to good effect. And the Anglo-French theme has continued throughout my career as well, so the experience of seeing these two nations work together has been really useful for me. It’s wonderful to travel through the tunnel now and I am very proud to have played a small part in building it.”

“When the tunnels were commissioned I felt a mixture of relief and pride,” remembers Lance. “I was proud to be involved with such a major project and relieved that it had finally been completed and was up and running. I am still proud to have been a part of it. It’s one of the greatest tunnels ever built.”

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