How fast can a passenger train stop?

Deutsche Bahn: Train too fast in the curve? "Inconceivable"

A train disaster comparable to that in Spain cannot occur in Germany. That said the Infrastructure Director of Deutsche Bahn, Volker Kefer, in a conference call arranged at short notice. “It is inconceivable for us that a train could take a curve too fast,” says Kefer. The German train control systems would prevent increased speed and automatically brake the train beforehand.

According to new information from the police, at least 78 people were killed in the train accident in northwest Spain on Wednesday evening. A long-distance train derailed in a curve at excessive speed. All 13 wagons including the two power cars were derailed. Some cars were completely destroyed.

According to preliminary information, the train should have passed the curve at a speed of 190 kilometers per hour instead of the permitted 80. Now the train driver is being investigated on suspicion of gross negligence. But the crucial question is why the Spanish train control system could not prevent the accident.

All DB passenger trains with train protection systems

In Germany, passenger trains are only operated with so-called train protection systems. They prevent a train from traveling faster than allowed. If the system detects that the speed is exceeded, the train is given a so-called "automatic brake". High-speed trains are monitored by a system that continuously monitors the speed online.

“If such a train is traveling five kilometers per hour faster than prescribed, the engine driver receives a warning signal. In addition, the train is slowed down, ”said Kefer. If a train approaches a curve or a construction site too fast, for example, the system would intervene and reduce the speed beforehand. The Eschede disaster in 1998 was not due to the train control system, but to a broken tire, said Kefer.

Even trains that are not traveling at high speed would be controlled by what is known as train control, also with regard to their speed. The system works in a similar way to the super express trains. If their electronic monitoring system fails, which is theoretically possible, they would be automatically slowed down to the maximum speed of the other trains of 160 kilometers per hour. According to Kefer, the systems are designed to be redundant. If one is no longer ready for use, another will take effect.

An attempted attack would be noticed immediately

He considers manipulation of the systems, for example in the context of an attempted attack, to be unlikely. "That would be noticed immediately," says Kefer. It is also unthinkable that a system could fail unnoticed. "There is constant online control as to whether the LZB control system for the high-speed trains is switched on." Any necessary emergency braking would be automatically initiated by the system, and human error is not possible, said Kefer.

However, until two years ago there were secondary lines in Germany that were not equipped with these monitoring systems. It was therefore possible that in 2011 the driver of a freight train near Hordorf in Saxony-Anhalt was able to run over two signals and then collide with a passenger train. Since then, the railway has completely upgraded all remaining routes, said Kefer.

In Santiago de Compostela, Spain, it was evidently the case that a system was installed at the scene of the accident that measures whether the prescribed speed is exceeded, but does not automatically brake the train. And when the train driver wanted to react, it was too late at the high speed to stop the train in time.