The ICE 1 was the flagship of German railways, and it rolled originally on monobloc wheels — single castings, wheel and running surface in one piece. Those wheels transmitted vibration, and the complaints were serious enough that engineers went looking for something smoother. What they adopted was a resilient wheel: a wheel body wrapped in a rubber damper roughly 20 millimetres thick, with a relatively thin steel tyre shrunk on outside it. The arrangement had worked on trams the world over. It had never been tested in Germany at 200 kilometres an hour.

Several consequences were missed. Under load the tyre flattened into an ellipse once per revolution, half a million times in a normal day's service. Unlike a monobloc wheel, this design let cracks begin on the inside of the tyre, where no inspection could see them, and as the tyre wore thinner the forces on it rose and made those cracks grow faster. The design, investigators concluded afterward, lacked an adequate margin of safety.

Trainset 51 was working ICE 884, the "Wilhelm Conrad Röntgen" from Munich to Hamburg, and had left Hanover at half past ten. About 130 kilometres short of Hamburg and six kilometres south of Eschede, the fatigue crack in the tyre finally ran through. The tyre peeled off, flattened, and was flung upward through the floor of coach one — the steel Dittmann found in the armrest.

The train kept running with the loose tyre riding inside it. At the Eschede switches, roughly two minutes later, the embedded steel struck the guide rail of the points and tore it out of the sleepers. The guide rail came up through the floor in turn, lodged in the carriage and lifted a bogie clear of the track. A derailed wheel then hit the lever of the second switch and threw it, and coach three was steered off the alignment into the piers of the road overpass. The bridge dropped onto the train. Coaches five and six were crushed beneath it; coach seven, coaches ten to twelve and the rear power car drove into the wreckage. Two of the dead were railway workers standing under the bridge. Eighty-eight people were severely injured.

None of this arrived without warning. At Deutsche Bahn's Munich depot, technicians were checking tyres with ordinary flashlights rather than metal fatigue detection equipment; the advanced testing machines had been in use earlier, but threw so many false positives that staff judged them unreliable and stopped.

In the week before the disaster, three separate automated checks flagged a defective wheel. Investigators later pulled the train's on-board maintenance log and found that over the previous two months, conductors and other staff had filed eight separate complaints about noise and vibration from the bogie that carried it. The wheel stayed on the train. Deutsche Bahn's position afterward was that its inspection regime had been proper for the time and no engineer could have predicted the fracture.

The rescue crews who reached Eschede could barely open the train. Its aluminium framework and pressure-proof windows, both designed for strength at speed, resisted cutting equipment in ways nobody had anticipated, and reaching trapped passengers took far longer than it should have.

The technical response was fast. Within weeks every wheel of that design in the fleet was replaced with monobloc wheels, and the entire German network was checked for switches sitting close to bridge piers or other obstacles. All trains were refitted with windows carrying deliberate breaking seams and a hammer beside them; the small marked panel now standard in German carriages dates from that morning. The legal response was slower and thinner. Deutsche Bahn paid 30,000 Deutsche Marks per fatality at first, later settling with survivors and families for more than 30 million US dollars, and the criminal case ended in an April 2003 plea bargain, dismissed without a verdict. The engineers each paid 10,000 euros.

Udo Bauch survived the crash and was left disabled by it. He built a memorial chapel near the site with his own money; it receives five to six thousand visitors a year. A year later an official memorial partly funded by Deutsche Bahn opened beside the line.

It is a field of wild cherry trees — 101 of them, one for each person killed, planted along the rails near the bridge, the switch itself in front. A stone gate carries an inscription. At the centre of the trees stands a wall listing the names of the dead, renovated in 2012. From the field a staircase climbs to the road, and in 2013, fifteen years after the crash, Deutsche Bahn's chief executive Rüdiger Grube stood here and apologised to the victims and their families.

On the far side of the road, a second flight of steps climbs the bank and stops. There is nothing at the top.