To improve mobility in cities in line with environmental goals, in urban traffic, trams represent an increasingly important means of transport. Due to the close interaction with other road users, this makes collisions with trams fairly frequent. This study has investigated accidents between trams and vulnerable road users resulting in personal injury, aimed at identifying priorities for simulating collisions between trams and pedestrians to assess passive safety measures. Tram accident data collection established throughout Europe from multiple sources and with varying degree of details, have been combined and analysed. These analyses comprise risk assessments per km-driven and general tram accident partner and site type evaluations, with more detailed analyses on accident site distance to the closest tram stop and injured body regions, respectively. In total, 7,535 tram-pedestrian accident resulting in 8,802 pedestrian injuries, collected in the year 2000–2021, was analysed. Accident risk ranges from 0.934 accidents per number of tram (million) km-driven, for slight injuries to 0.063 for fatal injuries. Pedestrians represent a large proportion of tram accident collision partners, especially for severe and fatal accidents. In accidents between trams and pedestrians, 3% of reported injuries are fatal, 23% severe and 74% minor. Generally, low-speed accidents close to tram stops often leading to minor injuries were observed to be of significant importance (<20m to the GPS location of a stop). Analysis of accidents was done bases on gender of the pedestrian showing overall similar involvements in accident with slight difference for various age groups and sites. Regardless of injury severity, the most frequently injured body region in accidents involving a tram is the head. Likewise, injuries sustained to the thorax, especially for higher injury severities are of high relevance, followed by injuries to the lower extremities. Based on this study, recommendations for developing reasonable tram-pedestrian accident scenarios for virtual testing can be derived for further optimisation of pedestrian safety of trams.
For the development of restraint systems, the initial posture and kinematics of the occupants immediately before the crash are essential. To predict the behaviour of vehicle occupants in pre-crash manoeuvres, volunteer tests under controlled boundary conditions to calibrate and validate active human body models are needed. The challenge in such experiments is to evoke a natural behaviour of the volunteers. The aim of this study was to investigate the potential of distractions via virtual reality (VR) in volunteer tests to study pre-crash kinematics. For this purpose, it was investigated if the volunteers are able to get immersed into the virtual reality using head-mounted displays to an extent in which they forget the laboratory environment and feel as if they are really sitting in an autonomous vehicle. A total of 27 volunteers took part in the study, and 10 different trials were carried out with each of them. In the baseline trial, no VR was displayed and the volunteers were made aware that the sled is going to start moving by a countdown. In trials 3–10, the volunteers were instructed to perform various tasks in virtual reality, which we have developed for this specific purpose. The physical platform on which they were sitting on began to move mimicking a braking maneuver as they performed a task. The peak forward head excursions resulting from the different trials were compared and showed significant differences between the baseline trial and the trials where they were distracted with VR. In contrast to our expectations, peak forward head excursions were overall significantly lower for the volunteers distracted by VR compared to the baseline trial. However, volunteers, who had significantly lower peak forward head excursions in the baseline trials showed higher peak forward head excursions in the VR trials comparable in magnitude to the other volunteers. All the volunteers answered in the questionnaire that their experience had been good and they were willing to participate in the study again. Further research is needed to understand the effect of the performed activities on the volunteer muscle activation and head excursions.
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