Channel Tunnel fire

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The Channel Tunnel fire of 18 November 1996 occurred on a train carrying heavy goods vehicles (HGVs) and their drivers through the Channel Tunnel from France to Great Britain.

The Channel Tunnel is a 50-km long, triple-tube, rail tunnel linking the English county of Kent to the French sous-préfecture of Calais. Four types of train run through the tunnel: Eurostar passenger trains, car transporter trains, HGV transporter trains (HGV shuttles) and freight trains of both national railways. The fire started on a truck being carried on an HGV shuttle.

Contents 1 Summary 2 Trains 3 Safety features at the time of the fire 4 Timeline 5 Firefighting 6 Casualties and damage 7 Consequences 8 Sources

[edit] Summary

The fire began after the train loaded and was travelling through the French terminal to the tunnel portal. The flames were noticed by security guards shortly before the train went underground. Although they raised the alarm, the train was well into the tunnel by the time the driver was advised that his train might be on fire. He attempted to drive the train to the other end, but an unrelated fault forced the train to make a controlled stop in the tunnel. After approximately 20 minutes of exposure to smoke-laden air, the passengers and crew evacuated into the adjacent service tunnel.

No one was killed during the fire, although seven people were taken to hospital suffering from smoke inhalation. The fire destroyed a locomotive and ten HGVs, caused major damage to approximately 1 km of tunnel infrastructure and severely tested the abilities of fire brigades from France and the UK.

After the fire, Eurotunnel made significant changes to its safety procedures and modified its HGV transporter wagons to incorporate water fog fire suppression.

[edit] Trains

The train that caught fire was HGV shuttle no. 7539. It was made up of two locomotives (one at the front and one at the rear of the train, with the driver in the front one), an amenity coach carrying the truck drivers through the tunnel and two rakes of HGV carrier wagons (rake is Eurotunnel's term for a collection of its specialized vehicle-carrying wagons). The rakes comprised a number of HGV carrier wagons (14 in the front rake, 15 in the rear rake) plus flatbed wagons at each end of each rake to load and unload the HGVs.

In total the train was about 800 metres long, with the driver in the front locomotive and all others (two crew and 31 passengers) in the front coach. 29 HGVs were located, one to a wagon, behind the front flatbed wagon.

One HGV in the consist was placarded as carrying dangerous goods (polystyrene beads, UN 2211). It was located almost exactly half-way along the train. The other 28 trucks carried a variety of loads, some combustible, some inert. They included cornflakes, washing machines, glucose, titanium scrap, pineapples, paper and frozen fat.

Other trains were in the tunnel at the time of the incident. There were three trains ahead of train 7539, all of which drove out of the English portal as normal. Two trains entered the tunnel behind the incident train: a lone locomotive directly behind train 7539 (from which the driver evacuated to the service tunnel) and a passenger train behind that (which reversed out through the French portal).

There were three trains in the other running tunnel travelling from Britain to France, all of which were affected by the fire in one way or another. Two trains were slightly affected by smoke as they passed through on their way to France, and one was instructed to stop in the tunnel near to the site of the fire to be used as a rescue train. It stayed there for slightly less than an hour before those evacuated from the HGV shuttle were loaded onto it.

[edit] Safety features at the time of the fire

The Channel Tunnel and the trains that run through it are equipped with a series of safety features.

The three tubes are linked together and each link has some form of isolation. The escape cross-passages link all three tubes together but are fitted with fire doors that are normally closed. The two crossovers are equipped with sliding doors that can be opened to allow trains to pass from one tunnel to the other or closed to separate the two tracks. The doors are normally closed, although on the night of the fire the doors at both crossovers were open.

The two running tunnels are linked by pressure relief ducts. These are normally open, and are equipped with motorized butterfly valves that can be closed remotely.

The service tunnel is ventilated to keep it at a higher air pressure than the two running tunnels. This normal ventilation system (NVS) runs continuously and means that whenever a cross-passage door is opened, air will flow from the service tunnel into the running tunnel.

The running tunnels are usually ventilated by piston action of trains, but there is also a supplementary ventilation system (SVS), consisting of variable-pitch fans at Shakespeare Cliff and at Sangatte. These can be set to supply or extract, and together can move air in either direction along either or both running tunnels. The SVS does not usually run, but a controller can switch the fans on, then change the angle of the fan blades to have them extract or supply air.

The traction system is divided into sections of 1500 m length, which can be remotely switched to isolate failed sections.

The tunnel has a network of firemains, one in each of the three tunnels, which are linked together at the cross-passages. There are hydrants at each cross-passage and at intervals of 125 m in the running tunnels. The firemain is divided into sections by valves so that leaking sections can be isolated for repair.

Control of the tunnel is split into two types of control centre. The main Rail Control Centre (RCC) directs the rail traffic and operates the signalling, traction, pumping, lighting and ventilation. There are RCCs in both countries, although only one is in charge at any one time.

Each country has a Fire Equipment Management Centre (FEMC) which looks after all fire hazards and fire alarms in the terminal and in the tunnels. Each FEMC controls equipment in its adjacent terminal and a portion of the tunnel, and is home to a small works fire brigade dedicated to the tunnel. Main firefighting effort is provided by the fire brigades of Kent and Pas-de-Calais.

Fire detectors are located at intervals of 1.7 km along the length of the tunnel. These consist of a series of different types of detector: optical, ionic and carbon monoxide. The system is set so that if any two go off together, it raises a confirmed alarm in the FEMC and RCC. If only one of the three goes off, it raises an unconfirmed alarm in the FEMC.

The locomotives are all equipped with halon gas fire suppression systems, as are the car transporters wagons. The HGV wagons are different: they are open to the tunnel. The amenity coach (where the truck drivers sit out the journey) has the same half-hour fire protection as the Eurostar carriages.

The tunnel is not equipped with an emergency station with water fire suppression (unlike the Seikan Tunnel and the unfinished Gotthard and Lötschberg base tunnels).

The tunnels are mostly lined with segments of extremely high strength concrete but are not protected against spalling, which occurred here and reduced the concrete to a thickness of 50mm. Common countermeasures against fire-caused damage to tunnel linings are described under fireproofing and fire-resistance rating.

[edit] Timeline

Train 7539 left the French terminal at 21:42 CET. It stopped for a short time at a red signal before entering the tunnel at 21:48.

At 21:47, four French security guards (one pair in a building, two others on patrol) noticed a fire in the tractor unit of an HGV approximately three-quarters of the way down the train. They estimated the flames to be about 2 m high.

As the train passed through the first few kilometres of tunnel, unconfirmed fire alarms were triggered each time it passed a fire detector.

At 21:51, the Rail Control Centre called the driver of train 7539 to inform him that there was a possibility that his train had a fire on board. He was told to continue through the tunnel, and that his train would be diverted to the emergency siding when he emerged into the open air at the UK side, at which point Kent fire brigade could attend to it.

At 21:52, a second train (consisting of a single locomotive) entered the tunnel behind train 7539. A few kilometres in, the driver encountered smoke thick enough to make him slow down. At the same time, one of the fixed smoke detector units in the tunnel triggered a confirmed alarm, indicating to the Rail Control Centre that there was definitely smoke in the tunnel.

In response to the confirmed alarm, the Rail Control Centre began to prepare for a fire in the tunnel, in case train 7539 did not make it to the other end.

• It ordered all trains to slow to 100 km/h;
• It closed all the butterfly valves in the pressure relief ducts (PRDs);
• It ordered the sliding doors at the UK crossover and French crossover to close;
• It switched on the lighting in the service tunnel and in the UK-bound running tunnel;
• It mobilised the works fire brigade at the French and British sides, who both set off for the midpoint of the service tunnel.

The RCC's actions were intended to isolate the two running tunnels from one another but were not completely successful. One PRD remained open, and the French crossover door did not close completely.

Shortly after train 7539 passed the French crossover, a safety system on the train issued a 'Stop' message to the driver. An alarm indicated that one of the propping loops on a wagon had failed, allowing a jack to drop out of its stowed position. The jacks are lowered to stabilize the train during loading and unloading but are raised when the train is moving, to reduce the risk of derailment if there is debris next to the track.

The driver followed Eurotunnel's standard procedure for the failure of a propping loop: he brought the train to a controlled halt, stopping it with the amenity coach next to one of the escape cross-passages. The train came to rest in the tunnel at 21:58.

The driver intended to uncouple the front locomotive and the amenity coach, then drive out of the tunnel leaving the fire and the HGV wagons behind. However, a few seconds after stopping, the traction power supply tripped out, stranding the train. The failure was later attributed to heating of a soldered connection in the traction power system.

When it stopped, the train was in French territory, approximately 19 km from the French portal, 32 km from the UK portal and 2 km west of the French crossover. The train spanned three cross-passages: the west cross-passage (CP4131) was next to the amenity coach; middle cross-passage (CP 4163) was next to the HGV carrying polystyrene; and the east cross-passage (CP4201) was next to the rearmost HGV.

The fire was on an HGV in the rear rake, close to CP 4201, either in the seventh HGV (carrying corn flakes) or the tenth HGV (carrying reels of paper). The fire was approximately 600 m from the front of the train, but the forward flow of air over the stopped train carried the smoke to the front and filled the tunnel ahead of the train.

As the air in the tunnel around the locomotive was filled with smoke from the fire, the driver could not see the number of the cross-passage he had stopped at. The Rail Control Centre was aware that he had stopped with the amenity coach next to one of two cross-passages (CP4101 or CP4131) but did not know which.

At 22:02, the Channel Tunnel's French works fire brigade entered the service tunnel with seven firefighters. The Rail Control Centre acted on the belief that the front of the train was next to cross-passage 4101, and directed the French firefighters to that cross-passage. At 22:03, the British works brigade entered the service tunnel as well.

At 22:05, the emergency services of Pas de Calais were alerted and instructed to attend an incident in the tunnel and take command of the event. One of the French commander's first acts was to ask that the tunnel's supplementary ventilation system (SVS) be operated. At 22:12, the Rail Control Centre started both SVS fans but the fan blades were left at zero pitch angle and had no effect on the direction of airflow in the tunnel. Air continued to flow forwards over the train, bringing smoke from the fire towards the amenity coach. Fortunately, the fire was sufficiently far back (600 m) that there was no significant heat coming forward.

While the French works brigade were on their way to cross-passage 4101, the air quality on the train deteriorated and those aboard became increasingly concerned about their safety. The driver was unable to leave the locomotive, even with his emergency breathing apparatus on: the train crew inside the amenity coach were unable to contact the driver due to a failure of the radio system. No one inside the amenity coach could see the adjacent cross-passage due to the smoke in the tunnel, and smoke was slowly coming into the amenity coach through small openings in the bodywork.

At approximately 22:05, the Chef de Train in the amenity coach opened one of the train doors to check if he could see the adjacent cross-passage. He could not, despite it being directly opposite the door, and although the door was open only for a short time, it allowed a large amount of smoke to get into the amenity coach. Passengers and crew began to breathe through cloths and to take air from floor level, beneath the layer of smoke in the carriage.

While waiting for the French works fire brigade to reach the scene, the Rail Control Centre spent some time arranging evacuation of the driver of the locomotive behind train 7539. The Centre also reconfigured the traction supply to allow the train behind the locomotive to reverse out. In addition, one of the Eurostar trains bound for France was brought to rest in the north running tunnel close to the site of train 7539, so that it could act as a rescue train if it was required.

At 22:21, the Rail Control Centre remotely opened the cross-passage doors at 4101 (where the amenity coach was believed to be) and at cross-passage 4131 (where it actually was). Clean air from the service tunnel began to flow into the running tunnel through both cross-passages.

When the French firefighters arrived at cross-passage 4101, they found an open cross-passage but no train. The sub-officer noted that the supplementary ventilation system appeared to be doing nothing, and requested a check on whether it was operating correctly. The Control Centre subsequently realized that the SVS fans were spinning but that the fan blades had been left at zero pitch. The SVS was configured correctly at 22:22 and finally created an air current that moved smoke from the fire away from the people on board train 7539.

When the Rail Control Centre opened the door in cross-passage 4131, clean air from the service tunnel blew out onto the side of the amenity coach. This cleared smoke locally and allowed the occupants of the amenity coach to see that they were right next to an open cross-passage. The staff in the amenity coach subsequently evacuated all the passengers into the service tunnel, where they spent the next few minutes coughing up the soot they had inhaled.

As the French works brigade made their way east along the service tunnel, they came across the evacuees near CP4131. They checked that the amenity coach was empty, and escorted the driver to safety. At 22:35, they closed the fire door in cross-passage 4131 and concentrated on assisting the worst-affected of the evacuees with oxygen. They were assisted by the works fire brigade from the British side, who arrived on the scene at 22:30.

Between 22:42 and 22:52, 27 walking wounded were loaded onto the rescue train waiting in running tunnel north. The train set off towards France at 23:08 and despite passing through a cloud of smoke in the vicinity of the French crossover, left the tunnel without incident.

The other seven evacuees, who were more seriously affected, remained in the service tunnel and were taken to France in service tunnel vehicles equipped as ambulances.

[edit] Firefighting

Having assured themselves that all aboard the train were now safe, the French and British works brigades began to investigate the fire. A crew of firefighters entered the tunnel near the front of the train and began walking towards the French portal. They came close to the fire after walking approximately 500 m, then turned back and reported that the seat of the fire was between the next two cross-passages (CP4163 & CP4201). Cross-passage 4131 was closed and all firefighting operations were moved east to the two cross-passages closest to the fire. Subsequently, Kent fire brigade began firefighting operations at cross-passage 4201 (downstream of the fire), and Pas-de-Calais fire brigade began firefighting operations at cross-passage 4163 (upstream of it). Overall control of the firefighting operation rested with Pas-de-Calais fire brigade.

For the next five hours, teams of firefighters from both countries attacked the fire from the two cross-passages. They worked in breathing apparatus, hampered by fallen cables, flapping rags of glass fibre (from the cable tray) and spalled concrete. Each shift of firefighters could work in the tunnel only for short periods of time before returning to the service tunnel.

The presence of hundreds of firefighters spread along half a kilometre of service tunnel caused huge logistical problems with supplies of BA sets, water and sanitation from both ends of the tunnel.

The water supply at the two cross-passages became significantly poorer when firefighting operations began, mostly due to leaking pipework in the south running tunnel. The number of jets was reduced to two until a Eurotunnel engineer reconfigured the valves to isolate the pipework between the two cross-passages. Once the section of pipe was isolated, water delivery improved substantially.

At 05:00 on 19 November, the fire was declared extinguished. Most firefighters left the scene at 14:50 that day, although the debris continued to cool for another day or so.

[edit] Casualties and damage

No one was killed during the incident, and only minor injuries were sustained, all consisting of smoke inhalation by those people on the train. The oxygen therapy provided by the French works fire brigade at the scene proved an invaluable benefit: after observation in various hospitals, the last (and most seriously-affected) person was discharged the following night (19 November). The light casualties are attributed to the presence of the pressurized service tunnel and the oxygen provided at the scene.

Despite working in excessively hot and wet conditions, with spalling concrete falling from above, no firefighter suffered serious injury during the operation to extinguish the fire.

Over approximately 50 m of tunnel, the 0.4 m thick tunnel lining was reduced to a mean depth of 0.17 m, with the thinnest area being 0.02 m. The chalk marl showed no signs of failing or collapsing, but colliery arches were subsequently installed to support the ground as a precaution.

Over a further 240 m (70 m towards Britain, 170 m towards France) damage to the concrete extended as far back as the first reinforcement bars, reducing the linings to a depth of 0.2–0.35 m. These segments were repaired in situ without additional ground support.

Superficial damage to the surface of the concrete segments was evident along a further 190 m of tunnel length.

In the vicinity of the fire, all services were destroyed. This included HV cables, LV cables, communications, lighting systems, traction and junction boxes over a length of 800 m.

500 m of track had to be replaced, as did 800 m of catenary, 800 m of refrigeration pipe and signalling equipment over a length of 1500 m. In all, four escape cross-passages and five pressure relief ducts had to be refitted with new doors and dampers.

The damage to the train was concentrated in the rear half. The front locomotive, amenity coach and front rake (including the truck carrying dangerous goods) suffered minor damage from heat and smoke: all were re-usable after thorough cleaning and minor repairs. The rear rake suffered major thermal damage: eleven wagons and the rear locomotive were scrapped, as were most of the HGVs.

[edit] Consequences

Three separate investigations were conducted. The first was a French judicial inquiry into the cause of the fire, the second was an internal inquiry by Eurotunnel and the third was an inquiry by the Channel Tunnel Safety Authority (CTSA), a bi-national body formed of personnel from British and French railway safety bodies, fire brigades and government departments.

In the immediate aftermath of the fire, all train services were stopped. Three of the four types of train service were resumed in stages over the following two months. Refurbishment work in the tunnel at the site of the fire meant that when train services restarted, single-line working of the north tube was used between the two crossovers. The refurbishment was completed in May 1997, after which the HGV shuttle service was allowed to restart.

The fire showed significant weaknesses in Eurotunnel's control procedures. The large number of duties carried out by the Rail Control Centre during the incident meant that some were not completed when they should have been. The CTSA's criticisms were all the more pointed because this aspect had been noted during an internal Eurotunnel assessment of the Control Centre earlier in the year. Additional staff, one of whom is dedicated to managing fire alarms, are now permanently on duty. The procedures for operating the ventilation system have been simplified.

Eurotunnel's policy of attempting to drive trains through the tunnel in the event of an on-board fire has been abandoned, as was the back-up policy of uncoupling the locomotive and amenity coach. In the future, trains will immediately be brought to a controlled stop and the occupants evacuated into the service tunnel under the direction of the Chef de Train. In addition, all HGV wagons have been fitted with water fog fire suppression systems, and the trains lengthened to provide more space between the first HGV and the amenity coach.

Liaison between Eurotunnel and emergency services has been entirely revamped. In addition, joint exercises and exchanges of personnel between the British and French fire brigades have been instituted, so that each has experience of the other's operational procedures.

Various other minor changes have been made which will have a significant impact on the progress of events in a similar situation. The illumination of the cross-passage markers has been improved and staff on board the trains provided with powerful torches. Responsibility for evacuating the train has shifted from the driver to the Chef de Train, and more train staff are now required to have first aid training.

[edit] Sources

• Channel Tunnel Safety Authority, Inquiry into the fire on Heavy Goods Vehicle Shuttle 7539 on 18 November 1996, May 1997, ISBN 0115519319
• BBC First Sight: How safe is the tunnel?, broadcast January 1997.
• Welsh, W., Channel Tunnel Fire (UK), contribution from Kent Fire Brigade to NEDIES project Lessons Learnt from Tunnel Accidents, 2001.
• Fudger, G., Implications for Procedures in all Road and Rail Tunnels, Seminar on Consequences of the Channel Tunnel Fire for all Road and Rail Tunnels, March 1998.
• Bradbury, W. M. S., The Channel Tunnel Fire: Design Implications for Other Tunnel Systems, ibid.
• Kirkland, C., The fire in the Channel Tunnel, Tunnelling and Underground Space Technology, vol. 17, pp.129-132, 2002.
• Liew, S. K., Deaves, D.M. and Blyth, A.G., Eurotunnel HGV fire on 18th November 1996 - Fire Development and Effects, Proceedings of the 3rd International Conference on Safety in Road and Rail Tunnels, ITC, 1998.
• Comeau, E., Chunnel Vision NFPA Journal, March/April 2002.
• Comeau, E. and Wolf, A., Fire in the Chunnel NFPA Journal, March/April 1997.
• French, S. C., Fire Safety in the Channel Tunnel - An Overview, Proceedings of the International Conference on Fires in Tunnels, Borås, Sweden, October 1994, ISBN 91-7848-513-4
• French, S. C., Heavy Goods Vehicle Test for the Eurotunnel Project, ibid.
• Beech, J., Lecture to the Institution of Mechanical Engineers, 1990.
• Kirkland, C. (editor), Engineering the Channel Tunnel, Chapman & Hall, 1995, ISBN 0-419-17920-8