Platooning will soon likely to be common on Swedish roads and the potential for fuel savings in the transport sector is high. This pre-study project explores the need for external signaling in platoons to avoid any cut-ins from surrounding vehicles whose drivers are unaware that their actions may cause a loss of fuel saving. Interviews with truck drivers created an understanding of how they experience the behavior of the surrounding traffic. The scenarios that are highlighted where unaware cut-ins may occur are mainly on-ramps and while overtaking on highway. Car drivers highlighted that overtaking may be a problem, especially on 2+1 roads. Communication needs elicited in workshops with drivers mainly concerned the movement patterns and properties of vehicles, e.g. speed, direction, gaps and length of the platoon. Barriers that were identified for external signaling is that trailers are constantly rotating between different tractors. This may require that more trailers than tractors need to be equipped with communication devices. To evaluate the potential impact of external signaling simulation could be used, where a driving simulator could be used to evaluate the perception of car- and truck drivers. Different means of communication, behavior, driving close together or lighting could be subject to evaluation. The long-term learning effect and behavioral adaptation to platooning in traffic is also important to study. It was found that there are large regional behavioral differences in traffic. Naturalistic data from the US, indicate that there are no cut-ins if the distance between trucks is < 30 m. In Europe, the data collected from ETPC indicate that there is up to one cut-in every 15 km on highways. The data from the ETPC is however very sparse compared to the US study. In Sweden, it does not seem to be a specific need for external signaling since very few cut-ins occur. In Europe, more cut-ins occur and external signaling could help to save fuel. It is however unclear what long-term effects external signaling may have. Further studies are suggested to study if short platooning distance (10-20 meters) is sufficient to deter surrounding traffic from cut-ins.
Strategiska innovationsprogrammet Drive Sweden