Eschede train disaster
The Eschede train disaster was the worst train accident since 1967 in German history and the world's worst high-speed train disaster. It happened on 3 June 1998, near the village of Eschede in the district of Celle, Lower Saxony (coordinates: 52°43′00″N 10°11′33″E / 52.71668148799412°N 10.1925033425165°E Coordinates: Extra unexpected parameters
). 101 people died and about one hundred were severely injured.
Chronology
The ICE high-speed train "Wilhelm Conrad Röntgen" was on the route from Munich to Hamburg. After stopping in Hanover at 10:30 am, the train continued its journey northwards. Six kilometres south of Eschede, near Celle, a wheel rim lining a wheel on the third axle of the first car broke, peeled away from the wheel, and punctured the floor of the car, where it remained embedded.
What followed was a chain of events that unfolded in seconds and yet would later take investigators months to piece together.
As the train passed over the first of two track switches, the embedded wheel rim slammed against the guide rail of the switch, pulling it from the railway ties. This steering rail also penetrated the floor of the car and became embedded there, lifting the axle carriage off the rails. At 10:59, one of the now derailed wheels struck the points lever of the second switch, changing its setting. The rear axles of car number 3 were switched onto parallel track, and the entire car was thereby thrown into the bridge pylons of a 300 metric tonne roadway overpass, destroying them completely.
Car number 4, likewise derailed by the violent deviation of car number 3 and still travelling at 200 km/h (125 mph), passed intact under the bridge and rolled onto the embankment immediately behind it. Three railway workers who had been working near the bridge were killed instantly. The tearing of the wagon hitches caused automatic brakes to engage and the undamaged cars 1 to 3 (as well as the front locomotive) came to a halt at the Eschede train station, some 3 km (2 miles) down the track. As the second half of car number 5 passed under the bridge, it collapsed, flattening the car completely. The remaining cars folded into the rubble in a zig-zag pattern, as the collapsed bridge had completely obstructed the track: Cars 6 and 7, the service car, the restaurant car, the three first class cars numbered 10 to 12, and the rear locomotive all derailed and slammed into the pile. The resulting mess was likened to a partially collapsed folding ruler.
An automobile was also found in the wreckage. It belonged to the three DB railway technicians and was probably standing on the bridge before the accident.
The crash made a sound that witnesses later described as "startling", "horribly loud", and "like a plane crash". Nearby residents, alerted by the sound, were the first to arrive at the scene. At 11:02 the local police declared an emergency; at 11:07, as the magnitude of the disaster quickly became apparent, this was elevated to "major emergency". More than 1000 rescue workers from the regional emergency services, fire departments, rescue services, police and army were dispatched. Some 37 emergency physicians, who happened to be attending a professional conference in nearby Hanover, also gave their assistance in the early hours of the rescue effort.
While many passengers and the driver survived in the front part of the train, there was almost no chance of survival in the rear carriages. One hundred and one (101) people died in the disaster, including the three railway workers who had been standing under the bridge.
Causative factors
Wheel design
The first generation ICE (ICE 1) trains were equipped with single-cast wheels, known as "monoblock" wheels. Once in service it soon became apparent that this design could, as a result of metal fatigue and out-of-round conditions, lead to resonation and vibration at cruising speed. Passengers noticed this particularly in the restaurant car, where there were reports of loud vibrations in the dinnerware and of glasses "creeping" across tables.
In trying to solve the problem, engineers decided that the suspension of ICE cars could be improved with the use of a rubber damping ring between a metal wheel rim and the wheel body. A similar design had been employed successfully in streetcars, though at significantly lower speeds. This new rim, dubbed a "wheel-tire" design, consisted of a wheel body surrounded by a 20 mm thick rubber damper and then a relatively thin metal wear rim. The new design was not tested at high speed before it was commissioned and brought into service, but proved successful at resolving the issue of vibration at cruising speeds.
At this point in time, no facilities existed in Germany to physically test the failure limit of a wheel and so complete prototypes were never actually tested. The design and specification relied heavily on available materials data and theory. Very few laboratory and rail tests were carried out, and the few that were did not measure wheel behaviour under extended wear conditions or outside of cruising speeds. Nevertheless, over a period of years the wheels proved themselves apparently reliable and, until the accident, had not posed any major problems.
The Fraunhofer Institute was charged with the task of determining the cause of the accident. It was later revealed that the institute had told the DB management as early as 1992 about its concerns vis-à-vis possible metal wheel rim failure. In the months leading up to the accident, the Hanover transit authority reported that the metal wheel rims employed in its trains were failing far earlier than expected based on the failure limit estimates; it unilaterally decided to replace the wheels much earlier than was legally required by the specification. In doing so, it reported its findings in a warning to all other users of wheels built following similar designs, including the German Federal Railway.
It was soon apparent that dynamic, repetitive forces had not been accounted for in the statistical failure modelling done during the design phase, and the resulting design lacked an adequate margin of safety. The following factors, overlooked during design, were noted:
- The metal wheel rims are flattened into an ellipsoid as the wheel turns through each revolution (approximately 500,000 times during a typical day in service on an ICE train), with corresponding fatigue effects.
- In contrast to the monoblock wheel design, cracks can also form on the inside of the metal wheel rim.
- As the metal rim gets thinner due to wear, the dynamic forces are exaggerated and the microfine cracks become larger.
- Flat spots and ridges or swells in the rim surface dramatically increase the dynamic forces on the assembly and greatly accelerate wear.
"Wheel-tire" designs have a long history of problems going back to the dawn of rail travel. Needless to say, they are no longer used in Germany.
Failure to stop train
By failing to stop the train, train crew and passengers may have allowed the wheel disintegration to become a catastrophic chain of events. Had the train been stopped immediately it is unlikely that the subsequent events would have occurred.
Conventionally, railways apply a stop and examine policy when there is strange behaviour or noises from a train. However, this was not the case aboard the ICE. Valuable time was lost when a passenger tried to warn the train crew about a large piece of metal coming up through the floor, instead of pulling the emergency brake himself. The train manager refused to stop the train until he had investigated the problem himself, saying this was company policy. This decision was upheld in court, clearing the train manager of all charges.
Other factors
The design of the overbridge may have also contributed to the accident because it had two thin piers holding up the bridge on either side, instead of the spans going from solid abutments to solid abutments. The Granville train disaster of 1977 had a similar weakness in its bridge. The bridge built after the disaster is a cantilevered design and does not suffer this deficiency.
Another contributing factor is the use of welds in the carriage bodies that "unzipped" during the crash (see Modern Railways December 2004, p16).
Consequences
Legal
In August 2002, two Deutsche Bahn officials and one engineer were charged with manslaughter. The trial lasted for 53 days with expert witnesses from around the world blaming each other for wrong approaches and bad results. The case was dismissed in April 2003 on condition of a fine being paid.
Technical
Within weeks, all wheels of similar design were replaced with monobloc wheels. The entire German railway network was checked for similar arrangements of switches close to possible obstacles.
Rescue workers at the crash site experienced considerable difficulties to cut their way through the train to gain access to the victims. Both the aluminium framework and the pressure-proof windows offered unexpected resistance to heavy rescue equipment. As a result, all trains were refitted with some windows that have predetermined breaking points.