by John Slater
The wealth of talent and expertise on this wonderful island never ceases to amaze. Dr Alastair Biggart, ‘retired’ tunnelling engineer, gave the Trust a fascinating, impressive talk on the construction of the Channel Tunnel. The weight of responsibility he carried as engineer for the UK part of the project, employed by Trans Manche Link, was awesome. The £21.2 billion, in 2015 money, was a big enough worry, anyway, never mind the need for safe operation for thousands of workers and subsequently, millions of users. This would alarm most people. Alastair appeared to have taken this in his stride as he does with other projects, world-wide!
Alastair spoke of the logistics problem of manufacturing and sourcing all the necessary components to the required specifications, in the right quantities, at the right time and in the right places.
The first tunnel was mooted in 1880’s but work was stopped when relations with France were such that it was deemed to be a security risk. More recently, a start was made in 1984. This was in competition with early planning for a third London Airport on Maplin Sands. These were both stopped in favour of Concorde, the remarkable, beautiful supersonic airliner. Yet another example of engineering excellence!
In 1984, the indomitable Maggie Thatcher persuaded Mitterand to join in the project and the joint Ango-French project was launched. On the 12th February, 1986, the Treaty of Canterbury was signed in the cathedral and remarkably, by 1991, one tunnel was completed. We provided much of the materials and the splendid high-speed loco’s.
The project was financed by private money, including 198 banks. At 12% interest this required £!m a day in interest. This was ‘swopped’ for equity, so the banks own it, resulting in a small profit. There are twin operating tunnels and a service tunnel for safe evacuation, if necessary. This has been successfully used for evacuation on three occasions, so far.
The terminal constructors used 3m tons of sand dredged from the Goodwins to fill low-lying areas. Great marshalling yards were then set out – no mean feat in its self.
£245 m in current prices, were spent on giant tunnelling machines The French had their own machines, to a slightly different design. Alastair mentioned that he worked in a similar way in Denmark, Spain and China. He is currently working 17.48 metres under Seattle.
The vast concrete factory, constructed on the UK side, on the Isle of Grain, used a specially strong mix with 160 different types of segments, 1000 a day, averaging 5 tons each.
Break through, was in December 1990 and they were spot on, both halves in alignment. Phew!
In the traditional manner, following the example set by Isambard Kingdom Brunel, a dinner party was held under the sea. Alastair amused us by saying that the British provided the tables and chairs and fortunately, The French provided the food and wine! Just one year later, tracks were in use with all of the overhead and other wiring in place and successfully tested. Incredible! 428 metres a week, 1700 metres a month had been constructed. Given the huge diameter of these tunnels, just think of the volume of spoil that had to be removed.
Alastair then moved on to Denmark, linking it to a huge, European rail network. Do we want the Isle of Man to be linked to Scotland? Alastair’s our man!
Our next meeting is on Wednesday, 17th June at 7.30 pm in the Centenary Centre. Dr Fenella Bazin is talking on Viking Art – Brutal Savages or skilled, artistic craftsmen? Come and make up your own minds. This will be excellent.