INTRO: Richard Hope examines the fallout from what could be the most costly accident in railway history

IN TERMS OF personal safety, Eurotunnel coped well with the major fire which raged through the rear half of a freight shuttle in the Channel Tunnel for several hours from 22.00 on November 18. After a frightening wait of some 15min in their fume-laden club car behind the front locomotive, all of the 31 passengers (mainly lorry drivers) and three crew were evacuated into the service tunnel. Smoke inhalation requiring a few hours in hospital was the worst injury suffered.

By contrast, the damage to the train and concrete lining of the running tunnel came as a severe shock to the company, which is currently negotiating with bankers the restructuring of debts totalling £8·7bn (RG 11.96 p699).

Both commercial and safety implications go far beyond this project. They will be debated anxiously wherever similar tunnels are planned, and also where lorries are carried by train.

Sequence of events

All appeared to be in order when a freight shuttle carrying 29 heavy lorries left the Calais terminal at 21.42, but security guards spotted flames and smoke towards the rear of the train as it entered the bore. The driver was informed at 21.51, and a fire alarm in the northbound running tunnel was confirmed at 21.53.

Operators at Eurotunnel’s Railway Control Centre closed the crossover doors and pressure relief duct dampers to prevent air flowing between the two running tunnels. Air intakes on passenger trains were closed by their drivers. A light Class 92 locomotive and a passenger shuttle following the freight shuttle were stopped, and all other trains (including the one on fire) were ordered to proceed out of the tunnel at 100 km/h. The Class 92 driver evacuated into the service tunnel, and the trapped passenger shuttle was driven out backwards by the chef de train in the rear locomotive.

Shortly after, the freight shuttle driver reported an alarm (later proved false) indicating that stablising jacks which support shuttle wagons during loading were no longer in the raised position. As this posed a derailment risk, he stopped a short way past the French crossovers with the club car accurately positioned by a cross-passage to the service tunnel.

The next move should have been to uncouple behind the club car and drive it out of the tunnel, but as soon as the burning wagons had stopped the catenary flashed over to earth, so there was no power. Attempts by the RCC to restore power failed.

The mass of air in the northbound tunnel, still flowing with the trains towards England, quickly enveloped the club car and front locomotive in smoke, and started to spread the fire forwards. The club car is designed to cope with this, but unfortunately the chef de train opened a door to try and locate the cross-passage. This admitted smoke, causing considerable distress to those inside.

By now, emergency fans at the two coastal shafts were battling to reverse the flow of air in the 39 km of running tunnel between them, eventually dispersing the smoke around the club car. Passengers and crew were evacuated into the service tunnel by 22.34, and taken back to France aboard a passenger shuttle which stopped in the southbound running tunnel to pick them up.

Rapid spread of fire

The first shock for Eurotunnel was the astonishing speed at which the fire was fanned to an inferno and spread along the train - first to the rear, then to the front - by the wind in the running tunnel.

The fire is believed to have started in a refrigerated lorry carrying pork fat. By the following morning, when the flames were finally extinguished, nine other lorries had been destroyed and the rear loco damaged; some wagons were so deformed that they had to be cut up on the spot.

In financial terms, the damage to the tunnel was far more serious. Where Eurotunnel had expected to replace catenary, cables and lighting, engineers found that temperatures exceeding 1000íC had buckled rails and caused the tunnel lining to crumble to rubble, exposing the reinforcing bars.

Eurotunnel’s Chairman, Patrick Ponsolle, estimated on November 27 that repairs to the tunnel would cost Fr300m to Fr400m, and put damage to the train at Fr50m to Fr100m. Much of this should be covered by insurance.

Restoring the tunnel may take five months. Until then, the Intergovernmental Commission’s Safety Authority will only allow Eurotunnel to operate six trains a hour in each direction because of concerns about evacuation. Rail freight recommenced on November 21, but the IGC would not allow Eurostar to resume until December 4, following a demonstration of interim evacuation plans. Passenger-carrying tourist shuttles restarted on December 10.

Freight shuttle doubts

Nobody can say when, or under what circumstances, freight shuttles might resume. Eurotunnel now has to convince a sceptical Safety Authority that carrying lorries on open-sided wagons is still acceptable, having originally proposed enclosed wagons until it was discovered that they would breach the 22·5 tonne axleload limit.

Eurotunnel’s first priority must be to devise ways of limiting the spread of fire along the train, perhaps through better control of the air flows. Secondly, there must be even more emphasis on keeping the burning train moving to protect the tunnel lining. Only when this is physically impossible should the driver uncouple behind the club car, without slowing down, and abandon the rest of the train.

And where does this leave the extensive mid-European Rollende Landstrasse operations, carrying 300000 lorries a year on flat wagons, with a good proportion passing through the 15 km Gotthard tunnel amid a dense stream of passenger and freight trains? Here there is no segregation of north and south tracks, no safe haven in a service tunnel, no forced ventilation, and no lateral walkway for evacuation. Fortunately, there have been no fires and no casualties since the first lorries passed through in 1968.

Concrete linings vulnerable

The extent to which fire can damage a concrete tunnel lining was revealed in June 1994, when a boring machine burned for several hours in the Storebaelt rail tunnel. In the worst damaged ring, spalling stripped away more than 200mm of the 400mm thick segments, which sagged to the extent that a depression appeared in the seabed 30m above.

A bulkhead had to be erected to permit compressed air working, and to guard against inundation, while a secondary iron lining was installed inside the damaged concrete rings. Recovery took 10 months. By contrast the damaged part of the Channel Tunnel is in stable chalk marl.

Eurotunnel accepts that emergency procedures must be revised, and that the 290 freight shuttle wagons (some not yet delivered) may have to be modified. However, should the Safety Authority insist on a new fleet of totally-enclosed wagons, the cost could exceed £300m. It is far from certain that Eurotunnel could borrow such a sum, yet the loss of revenue over the life of the concession would be many times greater. o

CAPTION: Top: Reinforcement bars are visible in the lining segments of the fire-damaged section of the tunnel

Above: Damage to the tunnel will take several months to repair. Some sag is evident (left) in the wagon covered by tarpaulins