Determination of the achievable capacity of an intelligent vehicle highway system (IVHS) was undertaken. The IVHS architecture proposed by earlier researchers in which vehicles coordinate their behavior to form short-headway platoons on an automated lane was examined. Although many estimates of potential capacity of such an IVHS has been derived, they all assume that steady-state flow already has been reached. In such an IVHS, entrance and egress of vehicles are the primary causes of traffic stream disturbance, ultimately dictating the flow rates that can be sustained reliably. Therefore the focus of the investigation was on entrance and egress strategies. A detailed simulator, SmartPath, models the passage of individual intelligent vehicles along the highway and was used to examine transient behavior of the traffic stream under various conditions. Three different strategies were examined for allowing vehicles to enter and leave automated lanes and measuring the corresponding maximum flow rates that are attained. The length of time it takes vehicles to enter an automated lane and therefore to build up high flows was also measured. Finally, the effects on flow of vehicles leaving an automated lane were measured, thus indicating that this would be the major source of traffic stream disturbance. It was concluded that, although maximum theoretical capacity cannot be attained, through prudent design of entrance and egress strategies, extremely high throughput can be sustained. (A)
Samenvatting