Above ground, the fire would have been minor. Breaking out deep below the English Channel, it has stranded thousands of travelers, imperiled millions of dollars in trade and starkly demonstrated the importance — and fragility — of Britain's only land link to Europe.
The Channel Tunnel remained closed Friday after a fire that started on a truck being carried on a train to France. Firefighters battled through the night trying to quell a blaze that caused temperatures to soar above 1,800 degrees in the tube 130 feet beneath the sea bed.
"This is going to cost the industry millions," said Kate Gibbs at the Road Haulage Association, a trade group for British transport companies.
As she spoke, hundreds of trucks loaded with everything from fruit to furniture sat along a stretch of highway that has become a virtual parking lot on the English side of the tunnel.
At London's St. Pancras station, passengers expecting to be whisked to Paris in a little over two hours were being told no trains would run until Saturday at the earliest. Almost 30,000 people had been due to take Eurostar trains between London, Paris and Brussels on Friday.
"It was going to be the journey of a lifetime, a dream holiday," said Richard Corbett, who had planned a 70th birthday trip to the French capital with his wife. "We came to go through the tunnel. It looks like it's going to be scrapped now."
A marvel of engineering, the "Chunnel" is actually three — two one-way rail tunnels with a smaller service tunnel running between them. The fire was in the England-to-France section, and operator Eurotunnel said it hoped to reopen the undamaged France-to-England tunnel as soon as Friday night.
Eurostar expects weekend disruptions
However, Eurostar, which operates the passenger trains that use the tunnel, said it did not know when its service would resume. It advised people with tickets for Saturday and Sunday to make other travel plans.
The tunnel has had a few fires in the past, including one in 1996 that disrupted freight traffic for months.
A tunnel linking France and England was a dream of Napoleon's — and a nightmare for many Britons, who for centuries have regarded the 20-mile-wide English Channel as a bulwark against conquest, rabies and other Continental ills.
The project finally gained official British approval in the 1970s but tunneling did not begin until 1988, under Prime Minister Margaret Thatcher — a committed skeptic of closer integration with Europe but also a champion of business and free trade.
British and French teams, tunneling from each end, met in the middle in 1990. The completed tunnel opened in 1994 and was hailed by Queen Elizabeth II as a mix of "French elan and British pragmatism."
It has not always been a business success, though.
Passenger numbers have fallen far short of the predicted 20 million a year, and Eurotunnel was heavily burdened by debt before reaching a restructuring deal last year. Ferries and budget airlines have retained a large chunk of cross-Channel passenger and freight business.
Nonetheless, the 30-mile undersea link has transformed travel between Britain and the Continent. Before the tunnel, a trip from London to Paris required an expensive plane ticket or a lengthy ferry crossing. Since the opening of the final stretch of high-speed rail line along the route last year, the train journey to Paris takes just 2 hours and 15 minutes, the trip to Brussels less than 2 hours.
Almost 8.3 million people used Eurostar trains last year — tourists on weekend breaks, business executives attending meetings, even cross-border commuters who live in one country and work in another.
Felix Marquardt, a Paris-based public affairs consultant, used to commute by train twice a week to his London office.
"There were times when I felt like I was taking the Tube," he said, referring to London's subway system. "There were people in my office in London who were driving 2 1/2 hours each way from the office. I was taking the train from Paris and it was taking me 3 hours to get to work. I felt sorry for people in Britain."
The tunnel has also been a boon to Anglo-French commerce.
Trade between Britain and France has tripled over the past 20 years, rising steeply since the tunnel was completed. France is Britain's third-largest export market, after the United States and Germany, and its third largest source of imports.
Last year 1.4 million trucks traveled through the tunnel on shuttle trains, carrying 20 million tons of freight — from chemicals, machinery and transport equipment to wine and beer.
Hundreds of trucks that had planned to use the tunnel sat along a stretch of highway near its English entrance Friday. Police said they faced waits of six to eight hours before they could get on ferries at Dover.
"The knock-on effect is going to be tremendous," said Gibbs at the haulage association.