Severe rear-end collisions caused by coaches and heavy goods vehicles (HGV) are an issue on German motorways. Modern Advanced Emergency Braking Systems (AEBS) for trucks that have already been used in passenger cars for a longer period offer the potential to reduce the number or mitigate the consequences of these serious accidents. Therefore, the European Commission passed Regulation (EU) No 347/2012 that by defining two successive approval levels obliges manufacturers to equip their trucks and busses with AEBS. The aim of this work is to investigate the impact of the regulation regarding the accident occurrence and thus to determine the effect of AEBS equipment in terms of reducing the number and severity of accidents. The work is based on the individual data of the German National Road Accident Statistics for the period of 2009 to 2018 and information of the Federal Motor Transport Authority regarding vehicle technology for vehicles which have been registered in Germany. The scope of the investigation includes all types of vehicles that are affected by the regulation. The relevant vehicle classes have been identified and delimited on the basis of the modes of transport contained in the Germany National Road Accident Statistics. As a result, one class for coaches and nine types of HGV were considered in the subsequent analysis. Primarily, AEBS is used to avoid rear-end collisions. Therefore, an accident scenario with rear-end collisions has been defined as well as two additional scenarios for lane departure accidents and other accidents. The investigation scope covers accidents with severe material damage in the narrow sense or personal injury that were caused by coaches or HGV on German motorways. Within the period under review (2009-2018) the number of accidents caused by coaches or HGV for the three defined scenarios slightly increased by 6.5%. The number of accidents caused by vehicles that were younger than five years decreased in the same period of time. Furthermore, a clear growth of rear-end collisions (+21%) was recorded while the number of accidents for the other two scenarios remained nearly constant. The stock of HGV with a maximum authorised mass of over 8 t has been increasing since 2012 with a particular increase in the amount of older vehicles. In contrast, the mileage-related accident rate remained on a nearly constant level while the accident rate relating to the vehicle stock decreased by 11.7% between 2012 and 2018. Odds ratios have been used to determine the total effect of AEBS on the development of accidents. The total effect indicates the changes in numbers of accidents of HGV and coaches affected by AEBS from the comparison period before the introduction of Regulation No 347/2012 to the analysis period after the introduction. Four groups were defined – one analysis group and three control groups that are not affected by the AEBS. The total effect of 37% (significant) has been determined from the individual changes within each group from the comparison period to the analysis period. Due to the very selective definition of the analysis group by only including vehicles that are definitely equipped with AEBS and by focusing on pure rear-end accidents which AEBS should address by design, a total effect of 37 % is in an expected range. However, the effect of the first approval level of the EU directive with relatively low performance requirements is assumed to be overestimated because among the vehicles with AEBS there are vehicles that already fulfill the performance requirements of approval level 2 and beyond. Besides, it was investigated if a reduction of the accident severity could be observed. The comparison of the analysis group and the first control group from the comparison period to the analysis period suggested a reduction of severe injuries. As a whole, the findings indicate that the compulsory equipment of coaches and HGV with AEBS is not only leading to a significant decrease in the number of rear-end collisions but also to a decrease of injury severity. a, the findings also show that even with the obligation of AEBS still a high number of accidents can be observed that are not avoided. This means that further action to improve traffic safety of heavy goods vehicles and buses have to be taken. (Author/publisher)
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