Creating a road safety performance index: theory and practice

Abstract

Over the last decade, a large number of safety performance indicators (SPIs) were developed based on the identification of various risk factors in road safety. Knowledge on these indicators is valuable in understanding the processes that lead to crashes and injuries, identifying corresponding interventions, and monitoring the effectiveness of the safety actions that are taken. Moreover, they are increasingly used as a supportive instrument for comparing the level of road safety between various countries. However, when a number of SPIs are considered for a particular risk factor, simple comparison per indicator may only show a small piece of the road safety picture, which can be misleading since different countries may operate in different circumstances with different focal points. Consequently, a composite road safety performance indicator (or index), which combines individual indicator values into one single score, is valuable to be developed in order to capture the multi-dimensional concept of road safety and to perform meaningful comparisons. In this paper, we provide the theoretical background of developing a composite indicator and introduce the different steps in the index construction. Moreover, the latest research on creating a road safety performance index is presented, and some theoretical and practical issues on this subject are discussed.