Evaluation of Mixed Automated / Manual Traffic

The design of Automated Highway Systems (AHS) involves the use of advancedtechnologies and automation to make the current transportation system more efficient interms of capacity, safety and pollution. The principal question is whether thesetechnologies will lead to any benefits in terms of safety, capacity and traffic flowcharacteristics as the degree of penetration in the current transportation system increases.There are a wide range of possible AHS configurations that vary from those with mixedautomated and manual traffic, to those with fully automated traffic lanes that arephysically isolated from manual lanes. The controversial class is where automated vehicles are allowed to mix with manuallydriven vehicles. The motivation behind this concept is that the current roadway will nothave to undergo any major changes. Vehicles will become more and more automatedindependent of AHS and should have the ability to operate in lanes with manually drivenvehicles. As the number of automated vehicles increases, the benefits of automation willincrease until saturation, where all vehicles will be automated in the same way with cruisecontrol, air-bags, etc. The purpose of this report is to investigate the requirements, safety issues andthroughput that will result from the mixing of fully automated vehicles with manuallydriven vehicles on the existing roadway system. Two scenarios are considered: scenario Ihas the fully automated vehicles mixing with the manually driven vehicles on the existingroadway system. In scenario II the roadway controls the traffic flow by communicatingwith the fully automated vehicles via a roadway/vehicle communication system and withthe manually driven vehicles through variable message signs.________________________________________________________________________*This work is supported by the California Department of Transportation through PATH of the Universityof California. The contents of this paper reflect the views of the authors who are responsible for the factsand accuracy of the data presented herein. The contents do not necessarily reflect the official views or