Identifying the Potential of Combined Road Safety Interventions - A Method to Evaluate Future Effects of Integrated Road and Vehicle Safety Technologies

Sammanfattning: Health loss in the road transport system is one of the leading global public health problems with approximately 1.3 million people killed annually. In order to have a systematical approach to improved road safety, it has become common practice to form road safety management policies that include target setting and evaluation. The overall aim of this thesis was to facilitate road safety management by developing a new method to guide stakeholders with decisions on the most effective interventions to improve road safety, or in the design of safety innovations. In this thesis, a new method to identify the potential of combined road safety interventions was developed and validated. Crashes were studied from a system’s approach perspective, and the integrated safety chain was used to derive a residual of crashes from a baseline based on assumptions regarding the progress of Safety Performance Indicators over the period studied. The characteristics of the residual fatal crashes in 2020 were then described and analyzed to identify future safety gaps. A validation of the method was conducted by taking into account actual interventions implemented between 2000 and 2010 and by reducing the fatalities in 2000 to a residual of crashes in 2010 and then comparing this to the true outcome of 2010. It was concluded that the method was found to give an overall valid explanation for the reduction of fatalities from 2000 to 2010. The main advantage of this method compared to previous methods is the ability to describe the characteristics of future crashes, and what measures would be effective in reducing them. Single vehicle and head-on crashes were estimated to be reduced most significantly from 2000 to 2010, largely as a result of the installation of median barriers and the fitment of Electronic Stability Control. In two studies, effect estimates of pedestrian friendly car fronts and Autonomous Emergency Braking (AEB) fitted on Heavy Goods Vehicles in head-on crashes were derived and these estimates can be applied in the method in future. It was also concluded that positive system effects can emerge between road and vehicle safety technologies. Speed management can enhance the performance of pedestrian protection which will be important for increasing safety for vulnerable road users. In addition, it was found that the overall effectiveness of AEB would increase if the proportion of loss-of-control scenarios is minimalized and that AEB could be very helpful for increasing the compatibility between passenger cars and Heavy Goods Vehicles. This thesis presents a new approach to evaluating future effects of integrated road and vehicle safety technologies. It can be summarized as; 1 – Highlight future potentials and safety gaps, 2 – Define and refine technological innovations and 3 – Guiding integrated interventions. It is recommended that the evolution of the transport system is taken into account when estimating the benefits of future technologies. Road and vehicle safety interventions should be designed in collaboration with stakeholders and combined in the best possible way in order to create positive system effects. There is also a need for accurate effect estimates as they form essential tools in the road safety management process.