Interactions Between Heavy Trucks and Vulnerable Road Users—A Systematic Review to Inform the Interactive Capabilities of Highly Automated Trucks

Abstract

This study investigates interactive behaviors and communication cues of heavy goods vehicles (HGVs) and vulnerable road users (VRUs) such as pedestrians and cyclists as a means of informing the interactive capabilities of highly automated HGVs. Following a general framing of road traffic interaction, we conducted a systematic literature review of empirical HGV-VRU studies found through the databases Scopus, ScienceDirect and TRID. We extracted reports of interactive road user behaviors and communication cues from 19 eligible studies and categorized these into two groups: 1) the associated communication channel/mechanism (e.g., nonverbal behavior), and 2) the type of communication cue (implicit/explicit). We found the following interactive behaviors and communication cues: 1) vehicle-centric (e.g., HGV as a larger vehicle, adapting trajectory, position relative to the VRU, timing of acceleration to pass the VRU, displaying information via human-machine interface), 2) driver-centric (e.g., professional driver, present inside/outside the cabin, eye-gaze behavior), and 3) VRU-centric (e.g., racer cyclist, adapting trajectory, position relative to the HGV, proximity to other VRUs, eye-gaze behavior). These cues are predominantly based on road user trajectories and movements (i.e., kinesics/proxemics nonverbal behavior) forming implicit communication, which indicates that this is the primary mechanism for HGV-VRU interactions. However, there are also reports of more explicit cues such as cyclists waving to say thanks, the use of turning indicators, or new types of external human-machine interfaces (eHMI). Compared to corresponding scenarios with light vehicles, HGV-VRU interaction patterns are to a high extent formed by the HGV’s size, shape and weight. For example, this can cause VRUs to feel less safe, drivers to seek to avoid unnecessary decelerations and accelerations, or lead to strategic behaviors due to larger blind-spots. Based on these findings, it is likely that road user trajectories and kinematic behaviors will form the basis for communication also for highly automated HGV-VRU interaction. However, it might also be beneficial to use additional eHMI to compensate for the loss of more social driver-centric cues or to signal other types of information. While controlled experiments can be used to gather such initial insights, deeper understanding of highly automated HGV-VRU interactions will also require naturalistic studies.

Mortality due to traffic accidents in Colombia: Profiles of pedestrians and cyclists, 1998-2019

“…Although riding a bicycle and walking have been promoted as active transportation means to improve health and environmental conditions throughout the world, 16,17 there are few research studies focused on these road actors in lowmiddle countries, 16 perhaps due to the significant attention directed to the accidents involving motorcyclists, drivers and passengers of vehicles.…”

“…18 The spatial separation of the transportation means might improve people's sensation of safety and prevent accidents and collisions. 16 Accident prevention might increase the willingness to walk and ride bicycles. 16 To such end, strategies that allow for improving road design, road education, and citizen culture should be adopted.…”

“…16 Accident prevention might increase the willingness to walk and ride bicycles. 16 To such end, strategies that allow for improving road design, road education, and citizen culture should be adopted. It can be very useful to adapt to the local reality of successful experiences from countries such as Spain, which, although still reporting significant mortality rates, have shown effective strategies to reduce accidents and mortality due to this cause.…”

“…It can be very useful to adapt to the local reality of successful experiences from countries such as Spain, which, although still reporting significant mortality rates, have shown effective strategies to reduce accidents and mortality due to this cause. 16 Regarding the socioeconomic conditions, many low-and middle-income countries lack policies to improve safety for pedestrians and cyclists, or such policies are not complied with (or enforced) by the various actors. 26 Especially in these countries, walking is a popular daily activity that offers extensive benefits for health and which, in addition, represents for many their only option to commute to the places they need for social functioning (schools, work, family, recreation).…”