It had never happened before. In seven years of service, no one had ever been killed on an ICE train. The super-fast, state-of-the-art Inter City Express (ICE) trains of Deutsche Bahn (German Railways) had covered hundreds of thousands of kilometers over a network of lines that connected important cities in Germany and Austria. Many thousands of passengers had safely reached their destinations.

The Inter-City Express (ICE) was developed in the early 1980s in an effort to upgrade existing trains and to provide high-speed rail service, as Japan had already done in 1964. The ICE was able to run at conventional speeds (below 200kph or 124mph) on existing tracks and up to 280kph (174mph) on the new high-speed tracks. During the 1990s, the ICE expanded throughout Germany and into neighboring Switzerland, Austria, Belgium, and the Netherlands.

By the late 1990s, the ICE, operated by Deutsche Bahn Fernverkehr, provided daily luxury rail service on over 100 trains. Amenities included a dining car, telephone services, in-seat video and audio entertainment, and a smoking area. These deluxe accommodations and a perfect safety record helped boost German rail travel by 30 percent during the decade. But the euphoria would soon come to an end.

On the morning of June 3, 1998, ICE train 884, the “Wilhelm Conrad Rontgen” (WCR), which consisted of a single locomotive pulling 12 cars, including passenger coaches, a service car, a restaurant car, and the rear locomotive, made a quick stop in Hanover at 10:30 AM before continuing north towards Hamburg—its final destination. On board the ICE from Munich to Hamburg were 287 people traveling at 200 kilometers per hour (125 mph).

Traveling northward, the WCR was four miles outside of Eschede, in Lower Saxony, Germany, when, at just before 11:00 AM, a wheel rim on the first passenger coach peeled away from the wheel body, puncturing the floor and becoming embedded. A passenger reported to the train crew that the piece of metal had come up through the floor, but the train manager let precious time elapse by insisting on investigating the damage himself before stopping the train.

The train continued to travel approximately two miles until it passed over the first of two track switches. The embedded wheel rim slammed against the guard rail of the switch, pulling it away from the railway ties. The switch’s steering rail penetrated the floor of the first coach, lifting the axle carriage off the rails. One of the derailed wheels struck the lever of the second switch, which changed the switch’s setting.

The rear axles of the third coach were switched onto a parallel track, twisting the coach perpendicular to the rails and sending the car careening into the pylons of a 30-metric-ton roadway overpass just beyond the second switch, toppling it onto eight rear wagons in a deathly jumble that unfolded in only four seconds.

Coach four, derailed by the violent deviation of car three, traveled underneath the bridge, impacting an embankment and killing three railway employees who were working nearby.

Coach five passed under the weakened bridge as it collapsed, crushing the car completely. The remaining coaches, including the service car, restaurant car, three first-class cars, and the rear locomotive, jackknifed into the collapsed bridge in a zigzag pattern.

Passengers had heard abnormal noises but had not triggered an emergency stop. The front unit, powered via overhead electrics, came to a stop two kilometers (1.24 miles) beyond Eschede, alone.

By 11:07 AM, only 37 minutes after the WCR left Hanover Station, the police declared a “major emergency” and dispatched rescue teams. Over 1,000 rescue workers descended on the accident site. Despite their efforts, 101 people lost their lives, and 88 more were seriously injured in the mishap. The derailment at Eschede was Germany’s worst train accident since World War II and left Deutsche Bahn facing deep scrutiny over design and safety.

During the rescue effort, emergency workers found it difficult to remove victims from the wreckage because of pressure-resistant windows and the railcar’s rigid, aluminum frames. As a result, Deutsche Bahn subsequently replaced these windows with a new design that included predetermined breaking points to allow for easier access to trapped passengers.

What had caused this high-speed train—the technological marvel of rail travel—to derail in such a horrific fashion?

The Investigation and Causal Factors in the Disaster

Survivors in a self-help network that included relatives of those killed, accused state-owned Deutsche Bahn of ignoring material fatigue during previous wheel checks and failing to compensate them adequately.

The Fraunhofer Institute in Germany was tasked with the accident investigation and traced its cause back to an improper application of a streetcar wheel design. First-generation ICE trains were made with single-cast or “mono-block” wheels. Engineers realized, however, that this design could result in metal fatigue and out-of-round conditions, which caused vibrations at cruising speeds. The mono-block wheel design was modified to include a rubber damping ring 20mm thick between the metal wheel rim and the wheel body.

Researchers later learned that, although it reduced vibrations, this new design weakened the wheel, making it much more dangerous than the original. Normal operational wear further weakened the modified (thinner) wheel rims on the WCR, causing one to separate from the wheel body and become embedded in the floor of the first passenger coach.

A contributing cause was indeed the flawed emergency operating procedures. Had the train been stopped immediately when the wheel disintegrated, the accident might have been avoided, and countless lives would have been saved. Unfortunately, Deutsche Bahn’s policy required that the train manager personally investigate any reports of trouble before halting the train. Passengers who witnessed the wheel failure could also have pulled the emergency brake to stop the train, but no one did. This failure to act proved to be fatal.

The Fraunhofer Institute identified underlying issues, including design verification flaws, that contributed to the derailment, namely poor design and insufficient testing:

  1. Unsuitability of the wheel design. The rubber cushioned wheels, which had been used successfully on streetcars, were not suitable for the heavier load of ICE trains operating at much higher speeds.
  2. The use of heritage as the basis for design verification. The ICE wheel-tire design was a heritage or legacy design from a streetcar application. NASA engineers often rely on heritage hardware and software. The lesson is clear to ensure that heritage designs are appropriate for current applications and especially operating environments.
  3. Inadequate testing. At the time, the rubber damping wheel design was adapted for high-speed rail use, Germany did not have the facilities necessary to perform complete operational (stress, fatigue, crack propagation) testing on the application of the rubber damping design, so many of the wheel-design decisions were based on analysis and theory rather than test data. The limited testing that was done did not account for the dynamic, repetitive forces that result from extended wear, extreme loads, and high-speed operation.
  4. Operational maintenance decisions. Operating margins and the determination of acceptable wear and tear for operational systems were in place with respect to the ICE wheels, but they were set far too low to prevent wheel failure. As early as 1992, the Fraunhofer Institute expressed concern that metal fatigue could lead to wheel rim failure. Experts warned that wheels should not be operated after being worn below 88cm (34.6in) in diameter (“as new” condition was 92cm or 36.2in), but Deutsche Bahn set the minimum limit at 85.4cm (33.6in). In the months leading up to the accident, the Hanover Transit Authority noticed that metal wheel rims were being worn down at a much faster rate than anticipated and decided to replace many of the wheels ahead of schedule. Unfortunately, the WCR’s wheels had not yet been replaced. The failed wheel measured 86.2cm (33.9in) in diameter.
  5. Rim fatigue.
    • Stress caused by wheel rims being flattened into an ellipse with each revolution (500,000/day)
    • Unseen cracks inside of wheel rim lead to failure
    • Thinning rim exaggerates dynamic forces causing micro-fine cracks to grow larger
    • Flat spots and ridges dramatically increase dynamic forces and accelerate wear
  6. Bridge Design/Switch Location. The placement of the switch (an inherent hazard for high-speed trains) in close proximity to overpass bridge supports contributed to the severity of the disaster. The failed overpass was supported by two thin piers instead of by spans anchored to solid abutments on either side. The bridge was rebuilt using a cantilevered design that would have been much less likely to collapse during such an accident.
  7. Lack of safety design features to detect and react to anomalous operational conditions. The change in vibration associated with a failed wheel rim could have been detected by safety monitoring sensors, which could have triggered a shutdown, broken command sequence, and/or alerted the engineer.
  8. Lack of emergency response policies, procedures, and communications. ICE workers were not trained in emergency response policies, procedures, and communications.

The After-Effects of the Disaster

After the accident, all ICE operations were suspended until a full-scale investigation could be completed. The wheel-tire design was completely discontinued throughout Germany and was replaced by the original mono-block wheel design. Meanwhile, Germany’s entire transit network was checked for similar arrangements of switches near possible obstacles.

In August 2002, three German railroad engineers—Joachim Thilo von Madeyski, Volker Fischer, and Franz Murawa, two former railroad employees who were in charge of wheel safety at the national railway and the manager of a firm that manufactures train wheels—rejected the charges of negligent homicide against them in statements read out by defense lawyers. Had they been convicted, they would have faced prison sentences of up to five years each. But, in 2003, the court abandoned the case against all three engineers, with each fined only €10,000 ($11,670).