The effect of an italian nationwide mandatory visibility aids law for cyclists

The role of conspicuity in preventing bicycle–motorized vehicle collisions has been the subject of investigation. To date, no study has evaluated the impact on bicycle safety of legislation imposing bicycling visibility aids. The aim of the present study is to investigate whether a legislation imposing high-visibility clothing for cyclist affects bicycle safety. Data on the monthly number of vehicles (including bicycles) involved in road crashes during the period 2001–2015 were obtained from the Italian National Institute of Statistics. Data were analyzed through an interrupted time-series analysis using a generalized least-squares method. Results revealed that the implementation of legislation imposing high-visibility clothing for cyclist did not influence the number of bicycles involved in road crashes as well as its proportion in the total vehicles involved in road crashes. The introduction of the legislation did not produce immediate effects, nor did it have any effects over time. Lack of knowledge on how the law was introduced, the degree of enforcement by the police, and behavioral changes in response to the law makes it difficult to attribute the lack of effect on bicycle crashes.