What factors across the whole sociotechnical system contribute to and create opportunities for rail accidents?
A paper to be posted in the coming weeks explored this question. While there’s newer and more extensive sociotechnical analyses of rail events and SPADs (signals passed at danger), I found this a nice little read.
Whereas earlier evaluations of SPADs focused heavily on individual-factors of the loco engineer (distraction, perception, interpretation etc.), this work, and others, found a far broader and deeper “complex interplay between social systems and technology”.
Using Rasmussen’s approach, they mapped out the interplay of factors across the sociotechnical domains.
They discussed three key areas that created the traps for loco engineers to result in a SPAD:
1. Changes to the layout and structure of the terminal environment;
2. Changes to policies and practices;
3. And generational turnover.
Many of these factors related to physical design and space constraints (signals placed near curves, or too low to the ground to be effectively seen), ill-designed platforms where signals were behind the cab, and hence couldn’t be viewed by the driver and other similar factors.
For policies and practices, a strong production pressure was present to meet community growth and schedules. Dispatchers were pressured to maximise through-put, meaning loco drivers were exposed to more signals, thereby increasing the chances of a SPAD.
Large generational turnover without effective transition planning resulted in loss of experienced rail staff with tacit knowledge trapped in their heads and not documented.
Poorly resourced training departments meant new starters lacked the necessary expertise.
Particularly, new dispatchers “inadvertently created traps for the locomotive engineers by routing trains in a way that increased the number of stop signals or taking away a permissive signal without giving the locomotive engineer enough time to react” (p9).
Finally, they argue that SPADs resulted from a “complex interaction in the normal behavior by employees at different levels of the organisation”.
For example, SPADs resulted from “Design of the infrastructure, decisions, equipment design, organisational policies, communication and coordination among teams and between departments and the day-to-day adjustments and accommodations made at all levels of the organisation” (pp9-10).
Ref: Authors: Multer, J., Safar, H., & Roth, E. (2015). In 5th International rail human factors meeting (London, UK).
Study link: https://rhf2015.exordo.com/files/papers/24/final_draft/024.pdf
SafetyInsights.org 
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