Re: [SystemSafety] Alton Towers was HF [No Classification]

From: Peter Bernard Ladkin < >
Date: Fri, 22 Apr 2016 18:25:25 +0200

On 2016-04-22 17:44 , Barnes, Robert A (NNPPI) wrote:
> It might fulfil the definition of a 'normal accident'

No, it's not a normal accident in the Perrow sense. The post by Carl shows this. In a normal accident, everything goes as planned and specified but something still screws up. If there is a clearly identified violation that is causal then it cannot be a Perrow normal accident.

I guess there is room at the conceptual boundary, where an action that is a Rasmussen "Migration to the Boundary" action is causal. Would this count as a normal accident?

> the limitations of the control system (no absolute determination of train position) will not have helped.

Right. Not determining positional information in a unique way is a factor in many rail accidents. The TransRapid accident in Lathen. Glenbrook. Waterfall. Alton Towers. Of these, Alton is the least bad, by far.

PBL Prof. Peter Bernard Ladkin, Faculty of Technology, University of Bielefeld, 33594 Bielefeld, Germany Je suis Charlie
Tel+msg +49 (0)521 880 7319 www.rvs.uni-bielefeld.de



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systemsafety_at_xxxxxx Received on Fri Apr 22 2016 - 18:26:21 CEST

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