A microscopic simulation model for merging control on a dedicated-lane automated highway system

The automated highway systems (AHS) are not designed as stand-alone transpo rtation facilities. Drivers will by necessity drive from their origins to t he AHS entrance, and from the AHS exit to their final destinations. Therefo re, the AHS will affect other transportation facilities, and should be inte grated with all other facilities in the transportation system. Interfaces c reate much of the congestion for today's transportation systems. Likewise, AHS interfaces may cause a similar problem, due to either AHS interactions with conventional systems or internal limitations from AHS merging capabili ties. If these problems exist, either the AHS or the conventional road netw ork cannot function properly. Consequently, the system as a whole may break down and the AHS could potentially become a detriment to the overall trans portation system. Clearly, not enough is known about the automated merging process to determi ne what conditions would lead to congestion at interface points. The curren t macroscopic analysis techniques assume parameters that are not applicable to an AHS, and no detailed AHS merging models have been developed and vali dated. This paper addresses the interface problem between an AHS, and conve ntional roadway. Specifically, it presents a microscopic simulation model f or one scenario of the automated merging maneuver. The results of the model show that for low flows and conventional highway speeds, an one-lane AHS m erging section with a dedicated automated entrance ramp has many similar ch aracteristics as a two-lane conventional freeway with or without fixed-time ramp metering. However, when the conventional freeway starts to "break dow n" near its capacity, the AHS continues to perform with little delay. The m odel also validates that the minimum ramp length requirements are a functio n of the merging vehicle's speed, the mainline vehicles' speed, and the acc eleration and deceleration rates of the merging vehicle. (C) 2000 Elsevier Science Ltd. All rights reserved.