The paper investigates whether more meaningful interpretation of time headways could be achieved when vehicle identities are taken into account as opposed to the conventional headway studies with no vehicle identification. The idea of spotting those vehicles that are in close car-following fashion, through automatic number plate recognition (ANPR) technology, was the initial motive of the research. With the use of a set of ANPR data collected in the Republic of Ireland, a number of empirical observations were made, which, in turn, attracted further attention. It was found that the distribution of headways with respect to time was more skewed to the right compared with the overall distribution of all data that had no particular reference to the vehicle identities. It was also interesting to show preliminarily that the ratio of standard deviation to the mean of the time headways (when vehicle identities are taken into consideration) was smaller than that of the headways obtained from the overall population without any number plate identities. It is therefore highlighted that there is need for research to explore the issue further from both points of view of academic studies and enforcement bodies. (Author/publisher)
Abstract