Evidence-based road safety policy? Evidence-based transport policy? A discussion of randomised experimentation and meta-analysis in the evaluation of interventions

words): This paper discusses methods of evaluating interventions. Examples in the transport field might include improving compliance with speed limits, or boosting the use of public transport. In recent years there has been a push towards higher methodological standards in medical research, because of the biases that can easily creep into the comparisons that are of central interest in a research project. Particular features of this trend are (a) in the conduct of research, randomised allocation of the experimental units (e.g., people) to treatment or control groups, and (b) in synthesis of previous research, carrying out what is termed a meta-analysis rather than a review in narrative style, with the analysis giving much greater weight to studies that had good methodology than to those which did not. The phrase 'evidence-based' is used in this paper to refer to these features, not to a general hope that research and facts will influence policy. This paper documents the extent to which high methodological standards have been adopted in transport and transport safety to date, and attempts to assess what place they might have in future.