Determinants of following headway in congested traffic

Abstract

This paper reports on results of a study undertaken in the U.K. aimed at investigating factors affecting the car following process. An understanding of the factors affecting this complex decision making process is essential to a wide range of theoretical issues including driver workload, capacity and the modeling of freeway flow, as well as practical applications such as the design of in-vehicle driver aids and assistance systems, many of which have direct relevance to increasing driver safety. The study used an instrumented vehicle to collect time dependent following data for a group of test drivers. Data was collected on two differing types of high speed road, using six primary subjects who drove a test vehicle, supplemented by data on one hundred and twenty three drivers that were observed following the test vehicle. Examination was made of how the time headway chosen by a driver is influenced by a range of situational variables commonly believed to effect behavior, with four main findings. Firstly, headway was found to change according to the type of vehicle being followed (i.e. subjects followed closer to trucks than to cars), secondly, little variation was found with changes in overall traffic flow, thirdly, little correlation was found with road type, and lastly a distinct day-to-day variation in individual behavior was observed.

Understanding Driver Car-Following Behavior Using a Fuzzy Logic Car-Following Model

“…Both Tsukuba drivers and Southampton drivers spend more time with the short THW (0.5s to 1.5s). As mentioned in previous research (Brackstone et al, 2009), THW tends to decrease as velocity increases. Figure 7 presents the relative velocity-acceleration mapping obtained from the fuzzy inference specification in Tsukuba and Southampton.…”

Cooperative Adaptive Cruise Control: Critical Human Factors Issues and Research Questions

“…Research has shown drivers to be relatively accurate when judging distance to a preceding vehicle but poor when judging time (de Vos, Theeuwes, Hoekstra, & Coemet, 1997;Taieb-Maimon & Shinar, 2001). Furthermore, some studies have shown drivers to follow larger vehicles at shorter gaps even though visibility is reduced (Brackstone, Waterson, & McDonald, 2009;Sayer, Mefford, & Huang, 2000).…”

Test-Retest Reliability of Simulated Driving Performance: A Pilot Study

“…Whilst a high ICC coefficient was observed for TTC to lead vehicles indicating high test-retest reliability, the high CV value for this variable suggests a large intra-individual variation in car following behavior. Recent work by Brackstone et al (2009) suggests that drivers are inconsistent in their choice of headway, with individual variations above 19% in adopted headway observed between trials in their study. Collectively, these results suggest that driving headway is likely to be susceptible to intra-individual differences.…”