In the last few decades, many initiatives were taken world-wide to reduce traffic unsafety. However, in spite of these efforts the number of accidents and traffic casualties remains inordinately high. Therefore targets are set and measures are taken to increase traffic safety. The aimed reduction of the number of traffic accidents and casualties within a certain time frame often constitutes an extra motivation for concerned parties to make additional efforts and draw up a concrete road safety plan and take action. To meet the targeted objectives in Flanders, the Flemish government has formulated the Road Safety Plan Flanders (Department Mobility and Public Works, 2008) in which 33 road safety measures were presented. This policy has to ensure that the number of fatalities and seriously injured are pushed back to a maximum of 250 fatalities and 2,000 seriously injured in 2015 (Department Mobility and Public Works, 2008). In 2020, these numbers have to be reduced even further to 200 fatalities and 1,500 seriously injured (Flanders in Action, 2011). In this research, a model for Flanders is developed which enables us to quantify the impact on traffic safety in Flanders when considering a set of regional and locational measures. On the one hand, the used methodology allows us to gain insight in the degree to which the planned measures will contribute to meet the targeted road safety objectives and on the other, it allows us to compare measures with each other. More specifically, in this Flemish computational model, the impact of a set of measures is calculated step by step. The application focuses on a set of six road safety measures from the Road Safety Plan Flanders (Department Mobility and Works, 2008) which are being implemented on road segments on a regional or locational scale. Moreover, a distinction is made between three road types: highways, secondary roads and local roads. The methodology, which consists of 5 steps, was based on Reurings et al. (2009). (1) In the first step of the model a description is given of the traffic situation and the traffic safety situation in the reference year (2007). (2) Subsequently, the baseline prognosis is made. In this prognosis the number of injury accidents, fatalities, and seriously and slightly injured casualties is calculated for the period from 2008 until 2015, only taking into account changes in the number of vehicle kilometres and the autonomous risk change. (3) In addition to these two aspects, the measure prognosis also takes into account the impact of the set of measures. (4) This leads to a prediction of the reduction of injury accidents, fatalities and seriously and slightly injured casualties on road segments in Flanders in 2015, calculated based on the implementation of a set of measures (consisting of six measures) between 2008 and 2015. (5) Based on savings and investment costs, a cost-benefit analysis is illustrated. We would like to emphasize that the main focus of this study lies in the description of the methodology and an inventory of data needs. In this report the model is moreover implemented as well as possible by means of an illustration based on the most recent data sets which were available at the start of the study (end of 2010). Since the results of this illustrative calculation are strongly influenced by the many assumptions that had to be taken throughout the computational process, we want to explicitly emphasize that the obtained results only indicate a direction and should by no means be taken literally. The illustration is therefore a ‘proof of concept'. In general we can conclude that this computational model offers a lot of opportunities for policymakers to optimize and attune their policy to the targeted road safety objectives. Despite the relatively advanced development of the model, there are some aspects which have to be taken into account in future research and use. Examples are the high level of detail of the used data sets, the detailed description of the planned measures and the limited availability of (detailed) Flemish information on the effectiveness of measures and accident profiles. One of the big challenges for this methodology would be its implementation in a GIS-application. (Author/publisher)
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