To mark the 25th anniversary of the opening of the Channel Tunnel, here are 25 facts about the modern engineering marvel.
1. The Channel Tunnel is 50.5 kilometres long, making it the 13th longest tunnel in use (the longest is the Delaware Aqueduct, at 137 km), and the fourth longest used by rail passengers. It has the longest undersea portion of any tunnel in the world (37.8 km).
2. The project cost £4.65 billion (equivalent to £12 billion or $A22.3 billion today), 80 per cent more than expected. Construction took six years (1988-1994).
3. It was recognised as one of the "Seven Wonders of the Modern World" by the American Society of Civil Engineers, alongside the Empire State Building, the Itaipu Dam in South America, the CN Tower in Toronto, the Panama Canal, the North Sea protection works in the Netherlands, and the Golden Gate Bridge in San Francisco.
4. The first proposal for a tunnel under the Channel was put forward by Albert Mathieu, a French engineer – it included an artificial island half-way across for changing horses. Further proposals were considered by Napoleon III in 1856 and William Gladstone in 1865, while David Lloyd George brought up the idea at the Paris Peace Conference of 1919.
Ideas for a tunnel under the English Channel go back to the early 1800s. Photo: AP
5. At the height of construction, 13,000 people were employed. Ten workers – eight of them British – were killed building the tunnel.
A Channel Tunnel drill sits as a memorial to workers in Calais, France. Photo: Alamy
6. Englishman Graham Fagg and Frenchman Phillippe Cozette carried out the ceremonial break through on December 1, 1990.
7. They didn't quite meet in the middle – the English side tunnelled the greater distance.
8. The average depth of the tunnel is 50 metres below the seabed, and the lowest point 75 metres below. Much of the chalk marl spoil bored on the English side was deposited at Lower Shakespeare Cliff in Kent, now home to the Samphire Hoe Country Park.
9. There are actually three tunnels down there – two for trains and a smaller service tunnel that can be used in emergencies.
10. Eleven boring machines were used to dig the tunnel. Together they weighed a total of 12,000 tonnes (more than the Eiffel Tower), while each was as long as two football pitches. One from the British side remains buried under the Channel. Another was sold on eBay for £39,999 in 2004.
A worker during the construction in 1990. Photo: AP
11. An average of 60,000 passengers pass through the tunnel each day, along with 4600 trucks, 140 coaches and 7,300 cars.
12. Three fires have occurred (in 1996, 2006 and 2012) inside the tunnel that were significant enough for it to close. The most serious, on November 18, 1996, damaged 500 metres of the tunnel, affecting operations for six months. An automatic fire dousing system has now been installed.
13. A number of train failures have occurred. On December 18, 2009, five Eurostar trains broke down, trapping 2,000 passengers for 16 hours without power, and many without food or water.
15. The Olympic Torch travelled through the tunnel in 2012 on its way to host city, London.
16. Shuttle trains are 775 metres long – the same as eight football pitches.
17. The lining of the tunnel is designed to last for 120 years.
18. It takes around 35 minutes to travel the length of the Channel Tunnel.
19. The introduction of a pet travel scheme in 2000 has seen more than two million dogs and cats travel through the tunnel.
20. The Queen and President Mitterrand officially opened the tunnel on May 6, 1994. The royal party travelled from Waterloo to Calais at a sedate 129 km/h. The presidential party sped to the coast from Paris at 300 km/h.
21. In 2009, former F1 racing champ, John Surtees, drove a Ginetta G50 EV electric sports car through the service tunnel from England to France, as part of a charity event. He kept to the 50 km/h speed limit.
22. To commemorate the 2014 Tour de France, which started in Leeds, England and finished in Paris, Chris Froome of Team Sky rode through the service tunnel, becoming the first solo cyclist to do so. He didn't keep to the limit, reaching speeds of up to 65 km/h.
23. The Channel Tunnel has starred in a grisly crime TV drama, aptly named The Tunnel, which followed a British and French detective as they worked to find a serial killer who left the upper half of a French politician and the bottom half of an English prostitute at the tunnel's half-way point.
24. On a cheerier note, around 12 million roses are delivered through the tunnel every year for Valentine's Day.
25. A reported 26 per cent of trade in goods between the UK and continental Europe goes through the Channel Tunnel each year, which represents a total value of £120 billion annually.
See also: The world's greatest train journeys
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