Channel Tunnel is 20 years old: In numbers

It is 20 years since the Channel Tunnel was officially opened. Both Queen Elizabeth II and France's President Francois Mitterrand attended the initial ceremony in Calais on 6 May 1994, before travelling through the Tunnel, or le tunnel sous la Manche in French, for a similar event marking its opening, in Folkestone.

It is impossible to explain all 31.4 miles (or 50.5km) of the Channel Tunnel without using lots of numbers. So here goes.

Seven

A few years ago it was voted one of the seven wonders of the modern world by the highly respected American Society of Civil Engineers.

That puts it in the same league as the Empire State Building, the Panama Canal and the Golden Gate Bridge. (Also on the list by the way, the North Sea Protection Works, which is worth looking up online.)

830

At around 830m (that's 907 yards) Eurotunnel tell me their car trains are the longest in Europe. They're also pulled by the most powerful locomotives in the world.

A train leaves the French end of the tunnel

1802

They have been talking about a Channel Tunnel since the beginning of the 19th Century. Napoleon liked the idea but the Brits didn't fancy the prospect of being invaded from a giant hole.

Since then there have been dozens of proposed schemes.

They even dug half a mile underneath Kent in the 1880s, and the old tunnel is still there today. Again, a fundamental mistrust of the French stopped it in its tracks.

The best idea that I've read about though, (I do so hope it's true), was for an ice tunnel, that could be deliberately melted by switching off the refrigeration units if an invading army fancied sneaking across. Brilliant.

It has been suggested that a Channel Tunnel could have shortened World War One by two years because the British could have used it to supply their troops more effectively. Quite a sobering thought that, especially as we remember the 100th anniversary this year.

40

It runs 40m (131ft) under the seabed. None of it goes through water. I was allowed to take a stroll through the service tunnel. Honestly, it's spooky.

One

It was finished a year late.

Philippe Cozette (R) and Graham Fagg, who dug the last sections of the tunnel mark the 20th anniversary

4 billion

It cost £4bn ($6.7bn) more than the original estimate, and that's without interest payments.

2007

Buckling under the sheer weight of debt, the owners were stumbling towards bankruptcy until a last-minute restructuring in 2007-08.

2012

All things considered, 2012 was the first year that this leviathan of a project actually turned a profit. The owners now say they're going from strength to strength.

Three

There have been three fires caused by lorries on trains. They now have an intensive, automatic spraying system to douse any flames (on top of dedicated safety teams and equipment).

Employees work to repair damage caused by a fire in 2008

Also three

There are actually three tunnels. Two for trains and a smaller, service tunnel down the middle (the one I walked down).

It can be used as a "lifeboat" to get people out during an emergency.

That is what happened in 2008 after the worst blaze, when a lorry caught fire seven miles from the French entrance. It took months to repair the damage caused by the 1000C heat.

Two

Two of the 11, mighty boring machines used to dig the thing are still down there, buried. Funnily enough, they don't fit them with a reverse gear, so it was cheaper to put in a 90-degree turn and bury them in the wall, rather than dismantle them and bring them out.

The other machines are on show all over the place. At least one is a sculpture in the middle of a car roundabout in France.

A Eurostar train at St Pancras

A couple

Back in the early 1990s they didn't have the pinpoint tunnelling machines they have today. They used lasers to guide them but engineers didn't know for certain they'd meet up in the middle until a bloke with a pneumatic drill knocked through the wall, and didn't get wet. It turns out they were just a couple of millimetres out.

By the way, the Brits got a bit further than the French, so they didn't quite meet in the middle, but the French did face tougher geological and engineering issues (apparently).

85

Around 85% of the people taking their cars and vans through are basically from Britain. Only around 6% are French.

So it turns out we like driving in France far more than they like driving here. They must have seen the M25 (M6, A14 etc etc).

20

Years old today.