Assessing the impact of road safety policy measures at the regional level: modelling approach and application

Abstract

Methods estimating road safety effects are an essential prerequisite to scientifically assess the effects of policy measures. Starting from the regional road safety explorer model developed by the Dutch institute SWOV (Reurings and Wijnen, 2008), a computational model for the region of Flanders in Belgium is developed to assess the road safety effects of a set of measures at a regional level. The model consists of five stages: the reference situation, the baseline prognosis, the measure prognosis, the number of saved road safety outcomes and the cost-benefit analysis. The reference situation describes the current exposure (or the degree of participation in traffic) and the current road safety situation (in terms of road injury accidents, fatalities, severely injured and slightly injured persons) in the region. A division into three road types is made: highways, regional roads and local roads. Data about the traffic performance and road accident data are available for each individual municipality in the region for the reference year 2007. Disposing of road safety targets for 2015 on the one hand and a regional road safety action plan (Ministerie van de Vlaamse Gemeenschap, 2007) consisting of a set of measures on the other hand, interest is in evaluating road safety by 2015. In this respect, it is important to take the evolution in key underlying aspects into account. This occurs in the baseline prognosis. In particular, the evolution in kilometres travelled and the collective learning process caused by the growing knowledge of road users, the constant improvement of road safety education, better equipped motor vehicles and roads as well as legislation and enforcement are incorporated in the model. The measure prognosis relates to the situation after applying the measures on particular locations in particular years and estimating the effectiveness of this set of measures on road safety. A road safety measure can be applied at the regional level (thus for all municipalities) or at a local level (for one or a few specific municipalities). The main outputs of the model are the number of saved injury accidents, fatalities, severely injured and slightly injured persons in the region. By expressing both the saved road safety quantities in monetary values and incorporating the costs of the measures, cost-benefit ratios are calculated. This cost-benefit analysis determines whether the applied measures are cost-effective. Through this analysis, policy makers are assisted in selecting target oriented policies that make the most efficient use of resources.In this paper, the different phases of the model are demonstrated. Focus is on the road safety situation in Flanders in the period 2007-2015. The degree to which the postulated targets will be met is determined given that measures with respect to education, infrastructure, target groups, etc. are taken.