In 1802, during a brief lull in Britain's wars with France, a mining engineer named Albert Mathieu-Favier presented Napoleon with a plan for a tunnel under the English Channel. Horse-drawn coaches would rattle through by the light of oil lamps, chimneys would poke above the waves for ventilation, and an artificial island built mid-Channel would serve as a staging post where the horses could be changed. The peace collapsed, the war resumed, and the scheme died — but the idea proved unsinkable. For the best part of two centuries, engineers kept drawing tunnels under the Channel, and politicians kept burying them.
The Victorians came remarkably close. In the early 1880s a compressed-air boring machine designed by Colonel Frederick Beaumont chewed nearly two kilometres of chalk out from under the sea near Dover, while a French crew bored towards them from Sangatte. The geology was cooperating; the generals were not. A press and parliamentary panic about French armies marching through the tunnel forced work to stop in 1882, and military objection kept the idea frozen for decades. As late as 1974 a fresh attempt actually began digging, only for the British government to cancel it the following year as costs spiralled. When Margaret Thatcher and François Mitterrand finally signed the Treaty of Canterbury in 1986, the deal carried one condition Thatcher insisted upon: not a penny of public money. The tunnel would be financed entirely by private investors — a decision its shareholders would come to feel keenly.
Eleven machines, one grave
Construction began in 1988, and the engineering gamble rested on a single layer of rock: the chalk marl, a soft, clay-rich chalk that is nearly impermeable to water and carves like cheese. The alignment was chosen to stay inside that layer, on average around 45 metres below the seabed. There would be three tunnels, not one — two running tunnels for trains, and a smaller service tunnel between them for ventilation, maintenance and escape. Eleven tunnel boring machines did the work, launched from Shakespeare Cliff on the English side and Sangatte on the French, gnawing towards each other beneath the sea while other machines drove the sections under land.
On 1 December 1990 the service-tunnel crews met in the middle. Britain's Graham Fagg and France's Philippe Cozette broke through a final wall of chalk and shook hands in front of the world's cameras — the first dry-land connection between Britain and the continent since the Ice Age. The surveying, done in an era when no satellite signal could reach underground, was astonishingly precise: the two drives met within a few tens of centimetres of each other. The boring machines themselves met stranger fates. Recovering a machine the size of a factory from under the sea was judged not worth the trouble, so as the drives finished, British seaward machines were steered off the alignment, driven downwards into the chalk and entombed in concrete, where they remain to this day. Another machine, which had dug on the British landward drive, was eventually sold on eBay in 2004 for £39,999.
The price of a masterpiece
Queen Elizabeth II and President Mitterrand opened the tunnel on 6 May 1994. The finished system runs 50.45 kilometres from Folkestone to Coquelles, of which 37.9 kilometres lie under the sea — the longest undersea stretch of any tunnel in the world. A favourite quiz trap lurks here: Japan's Seikan Tunnel is longer overall, but less of it runs beneath the water, so each holds a different record. At its deepest point the Channel Tunnel lies about 75 metres below the seabed, some 115 metres below the sea's surface. The triumph had its costs. Ten workers, most of them British, died during construction. The final bill came in roughly 80 per cent over the original £4.7 billion estimate, reaching around £9.5 billion in 1990s money, and Eurotunnel's early years were a grim procession of debt restructurings — the trains ran beautifully while the balance sheet burned.
The tunnel has since shrugged off fires, storms and a pandemic, and the American Society of Civil Engineers named it one of the Seven Wonders of the Modern World. Eurostar passenger trains and Le Shuttle vehicle carriers now cross beneath the Channel in about 35 minutes — a journey Napoleon's engineer had imagined taking the better part of a day, with a change of horses on an island in the middle of the sea. Two centuries of schemes, panics and false starts ended not with an invasion but with a handshake in the chalk, deep beneath the fish.
Quiz nuggets
- Albert Mathieu-Favier proposed a Channel tunnel to Napoleon in 1802, complete with an artificial mid-Channel island for changing horses.
- Eleven tunnel boring machines dug the tunnel; some British machines were steered downwards and buried in concrete, while another was sold on eBay in 2004 for £39,999.
- Britain's Graham Fagg and France's Philippe Cozette shook hands at the service-tunnel breakthrough on 1 December 1990.
- The tunnel runs 50.45 km, with 37.9 km under the sea — the longest undersea section of any tunnel; Japan's Seikan Tunnel is longer overall.
- Queen Elizabeth II and President François Mitterrand opened the tunnel on 6 May 1994.