Safety evaluation of freeway interchange merging areas based on driver workload theory

Abstract

Prior safety evaluations of interchange merging areas have mostly focused on traffic conflicts and operating speeds, without considering how these factors can influence the driver workload. Researches regarding the level of driver workload have largely concentrated on urban roads, tunnel sections, and basic freeway segments, without considering the impact of merging traffic flows on safety. Therefore, this study has investigated how merging vehicles can impact through-driver workload and safety. Three independent field experiments were conducted on freeways, involving 18 drivers and 17 interchanges. The results showed that the vehicles merging onto freeway impact driver workload and driving performance, generating potential risk that cannot be ignored. Merging into the mainline traffic flow increases the through-driver workload to a higher level or even exceeds the safety threshold, despite there being better geometrical conditions of interchanges than those of basic freeway segments. When the volume of merging vehicles exceeds 564 pcu/h or the traffic saturation is above 0.485, driver workload rises above the safety thresholds and the driving risk is elevated, which potentially would lead to crashes. This study offers insights for more effective segment division of operating speed prediction, and dynamic risk management with regard to interchange safety.

Impact of Transition Areas on Driving Workload and Driving Behavior in Work Zones: A Naturalistic Driving Study

“…Our experimental results indicated that transition zone length, driving behavior, and lane closure form all have an impact on the driving workload and vehicle speed in the work zone. This experiment was conducted under free-flow conditions, and previous studies have indicated that the driving workload while merging is positively correlated with traffic volume [37], and an increase in traffic volume can lead to a decrease in vehicle speed. Part of the work zone can be borrowed from the opposite lane to form a cross-work zone, with short intervals between the transition area and median opening, which can result in a rapid rise in driving workloads within a short period of time, increasing traffic safety risks.…”

Study on Driver Behavior Pattern in Merging Area under Naturalistic Driving Conditions

“…Although the merging area account for a small proportion of the highway, trafc accidents occurred in this area account for a large percentage. For example, during the period from 2014 to 2016, the total length of interchanges in a province in eastern China accounted for about 9.5% of highway in this province but the number of accidents accounted for 34.5% of the total number of highway accidents, and it accounted for 24.95% of the total number of fatalities in the province [1]. In a statistical study in the United States, it also showed that accidents occurred in the highway interchanges accounted for 18% of the total number of accidents and the percentage of fatal accidents is 21.8% [2].…”

Assessing the Effects of Interchange Warning Systems on Driving Risk: A Driving Simulator Study

“…Te longitudinal and lateral vehicles in the intertwined area lack coordination [1], resulting in signifcant diferences in vehicle speeds and frequent lane changes [2]. Terefore, interchanges have become bottleneck areas that restrict the operational efciency and safety of highways, representing high-risk road sections where conficts and collisions are likely to occur [3,4]. Research indicates that the occurrence of accidents is infuenced by factors such as vehicle speed, trafc fow, driver characteristics, and road geometry.…”