Development of an adaptive reverse warning concept

Abstract

Five per cent of all fatal accidents involving a Heavy Goods Vehicle (HGV) and a Vulnerable Road User (VRU) occur when the vehicle is reversing, despite the low speed of the manoeuvre. The audible reverse warning commonly used is perceived as annoying, which increases the risk of the driver deactivating the warning and, in turn, decreasing the safety of VRUs. In addition, the audible reverse warning has received criticism for contributing to societal noise pollution, which is a human health issue. Furthermore, a new UN regulation concerning the audible reverse warning will be implemented shortly, which must be considered. Because of the stated reasons, Volvo Group Trucks Technology initiated this master thesis that aims to deliver a developed and evaluated concept of a reverse warning that enhances the safety of VRUs, considers VRUs’ behaviours, reduces noise pollution, and complies with regulations. Literature studies were performed to gather information about, e.g., warning signal design, human behaviours, and legal requirements of reverse warnings. Several observations of VRUs’ behaviour in situations with reversing trucks in city environments were completed. A sound experiment was performed in the central parts of Gothenburg, where 114 persons were observed. Nine interviews with truck drivers were conducted, and a survey with 37 respondents was sent out internally at Volvo Group. Both systematic and creative methods were used to generate concepts of a reverse warning. All generated concepts were evaluated through evaluation matrices, and the best concepts were evaluated by 20 participants in a virtual environment. The final concept consists of additional lamps with flashing lights on the sides and rear of the truck and a projected warning triangle on the ground in the truck’s rear. The warning triangle indicates the truck’s intended pathway and enhances the visual attention of the reverse warning. The recommendation for the audible reverse warning is to keep the current well-known beeping sound. However, the sound should be adapted depending on the ambient noise level and status of the truck, i.e., idling or reversing. An adaptive sound would decrease unnecessary noise pollution, as it would emit a lower sound level in low noise areas and while idling. Furthermore, this thesis work has shown a possibility to replace the existing reverse sound with a sound perceived as more pleasant that still warns VRUs about a reversing truck.