A systematic review of definitions of motor vehicle headways in driver behaviour and performance studies

Headway is a safety measure commonly used to investigate driving behaviour and driver performance. Its purpose reflect the following distance or time between leading vehicle in traffic. It therefore associated with drivers’ response time, such as braking swerving, during critical events. In literature, headway are defined different ways, despite standard definitions traffic engineering which prompted this systematic review of across range study designs, order recommend approaches improve accuracy reproducibility road contexts. PRISMA guidelines were followed search four databases (EMBASE, COMPENDEX, SCOPUS MEDLINE) for studies that reported on headways discussed methodological approaches. The filtering abstracts identified 110 articles qualitative synthesis. Four broad measuring detected: using simulation, roadside external features, on-road on-vehicle features. Studies coded whether they included written explanation, mathematical statements, pictorial depictions headway. Only 49.6% contextualised sufficiently reproducibility. Reproducibility crucial accurate interpretation research findings comparisons studies. recommended should a) exclude parts lengths, b) include reference points (e.g., bumper/axle/rear), c) have consistent terminology, d) devices report precision study’s findings.