Thursday, 11 February 2021

System safety

 A couple of decades ago, a company was working on a new transport system that was *the future*. It offered fast, silent, and comfortable transport that had the potential to replace both rail and air.

They got millions in funding, and developed a fully-functioning record-breaking prototype.

A publicity document (1) mentioned 'safety' several times. It claimed:

"Collisions between (the) vehicles are also ruled out due to the technical layout of the system and the section-wise switching of the ”guideway motor“. The vehicle and the traveling field of the guideway motor move synchronously, i.e. with the same speed and in the same direction. Additionally, the section of the longstator linear motor in which the vehicle is moving is only switched on as the vehicle passes."

In other words, you can only have one vehicle on a track at once. This sounds brilliant, as you can only have a collision if two vehicles are on the same track, and the system does not allow two vehicles on the same section of track.

The system was the German Transrapid Maglev system. 

In September 2006 (2), a Transrapid Maglev vehicle was in a collision at Lathen (3), killing 23 people. It collided with a maintenance vehicle on the track; a maintenance vehicle that did not depend on power from the track, and therefore 'defeated' the inherent safety systems mentioned in the paragraph above. Add in an earlier-than-usual Maglev test run, and multiple staff errors, and you had a tragedy. 

No-one wanted the crash to occur; it was an accident, and yet it was totally caused by Human error, not an act of nature. The systems were not in place to prevent it.

What can we learn from this? Simply, safety is difficult. Human and technical errors compound safety issues, and therefore you require safety in depth with many fail-safes. These lessons have been learnt the hard way over a couple of centuries on the 'traditional' railway; they should not be forgotten by new systems, as the lessons are often paid for in human blood.

Most of all, safety has to be built-in to the system, not an afterthought. No system can be made safe by liberal applications of handwavium. And I fear this is a major issue with the proposed Hyperloop systems.

(1): TRI_Flug_Hoehe_e_5_021.pdf

(2): Sadly, the document is undated. However, it obviously dayes from before the crash.

(3): https://en.wikipedia.org/wiki/Lathen_train_collision

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