Microscopic Traffic Behaviour near Incidents
Much of the delays on road networks are caused by incidents. This is partially caused by blockage or closure of lanes, but also by the change of driving behaviour in the remaining lanes. This contribution analyses traffic flow conditions near an incident both microscopically and macroscopically. A theory is proposed to describe drivers’ behaviour, which is tested using traffic data of individual vehicles, collected using a helicopter. A bimodal headway distribution is observed, centred around two mean values, 2 seconds and 4 seconds. To understand the underlying mechanisms a car-following model is fitted to the drivers’ behaviour. The model parameters show that the reaction time is much higher than usual. Using this model-based analysis, we conclude that the incident distracts the drivers and less attention is paid to the driving process. The consequence is that the queue discharge rate for the unblocked lanes is 30% lower than the usual queue discharge rate per lane.
KeywordsAverage Speed Incident Site Reaction Time Distribution Transportation Research Record Incident Location
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This research was supported by the research program Next Generation Infrastructures, the Transport Research Centre Delft and the research program Tracing Congestion Dynamics – with Innovative Data to a Better Theory (sponsored by the Dutch Foundation of Scientific Research MaGW-NWO). The comments of the anonymous reviewers were also gratefully acknowledged.
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