Reverse invention: An inductive bottom-up strategy for safety rule development

This article presents a case study of four safety rule modification processes in the Norwegian railway system and their results. Special attention is given to the ambition to change the tradition of the system from predominantly experience based prescriptive rules towards risk based outcome-oriented rules. This can be seen as an introduction of a deductive and risk based top-down approach to rule development. The cases met this challenge with a strategy given the name “reverse invention”. This strategy can be seen as an inductive bottom-up approach to rule development, where existing prescriptive rules and railway knowledge served as the core fundament for development of outcome-oriented rules. Risk analyses served as supplement in the work and were used differently in the cases. The strategy brought forth knowledge associated with existing prescriptive rules. All cases found it useful to combine prescriptive rules with outcome-oriented rules. Compared to the ambitions of the projects the existing prescriptive rules appeared remarkably persistent. The main argument for this result was characteristics of the Norwegian railway system, such as needs for coordination with limited opportunities for communication, needs to make fast decisions, competency of the rule followers and rule followers who wanted clear instructions.