Arnab Bose

Analysis of traffic flow with mixed manual and semiautomated vehicles

The introduction of semiautomated vehicles designed to operate with manually driven vehicles is a realistic near-term objective. The purpose of this paper is to analyze the effects on traffic-flow characteristics and environment when semiautomated vehicles with automatic vehicle following capability (in the same lane) operate together with manually driven vehicles. We have shown that semiautomated vehicles do not contribute to the slinky effect phenomenon when the lead manual vehicle performs smooth acceleration maneuvers. We have demonstrated that semiautomated vehicles help smooth traffic flow by filtering the response of rapidly accelerating lead vehicles. The accurate speed tracking and the smooth response of the semiautomated vehicles designed for passenger comfort reduces fuel consumption and levels of pollutants of following vehicles. This reduction is significant when the lead manual vehicle performs rapid acceleration maneuvers. We have demonstrated using simulations that the fuel consumption and pollution levels present in manual traffic can be reduced during rapid acceleration transients by 28.5% and 1.5%-60.6%, respectively, due to the presence of 10% semiautomated vehicles. These environmental benefits are obtained without any adverse effects on the traffic-flow rates. Experiments with actual vehicles are used to validate the theoretical and simulation results.

Analysis of traffic flow with mixed manual and semi-automated vehicles

The paper analyzes the effects on traffic flow characteristics and environment when semi-automated vehicles with automatic vehicle following capability (in the same lane) operate together with manually driven vehicles. We show that semi-automated vehicles do not contribute to the slinky effect phenomenon observed in todays highway traffic when the lead manual vehicle performs smooth acceleration manoeuvres. We demonstrate that semi-automated vehicles smooth traffic flow by filtering the response of rapidly accelerating lead vehicles. Using simulations we show that the fuel consumption and pollution levels present in manual traffic simulated using a car following model that models the slinky effect behavior observed in manual driving can be reduced during rapid acceleration transients by 7.3% and 3.8%-47.3% respectively, due to the presence of 10% semi-automated vehicles. The data obtained are qualitatively valid and demonstrate the beneficial effect of semi-automated vehicles in mixed traffic in improving air quality and fuel consumption.

Evaluation of the environmental effects of intelligent cruise control vehicles

Intelligent cruise control (ICC) vehicles are already commercially available in Japan and should be ready for the North American market by next year. Although the controllers are local and string stable, it is not clear how the vehicles perform environmentally. It is shown that ICC vehicles can accurately track a lead vehicle and attenuate position errors generated by the lead vehicle during smooth transients. Furthermore, the smooth response of ICC vehicles designed for human factor considerations filters out traffic disturbances caused by rapid acceleration transients. Such ICC vehicle properties have beneficial air pollution and fuel consumption effects that are significant when the manual vehicles perform aggressive rapid acceleration maneuvers. These results are obtained using the Pipes human driver vehicle following model, which models the slinky-type effects observed in today’s manual driving. The response of the Pipes model is compared with that of human drivers. The Pipes model is observed to give a smooth approximation of human driver response during transients. Simulations have demonstrated that the fuel consumption and pollution levels present in manual traffic can be reduced during rapid acceleration transients by 28.5 percent and 1.5 to 60.6 percent, respectively, by the presence of 10 percent ICC vehicles. Experiments with actual vehicles are used to validate the theoretical and simulation results.

ISSUES AND ANALYSIS OF MIXED SEMI-AUTOMATED/MANUAL TRAFFIC.

The design of Automated Highway Systems (AHS) involves the use of advanced technologies and automation to make the current transportation system more efficient in terms of capacity, safety and pollution. The principal question is whether these technologies will lead to any benefits in terms of safety, capacity and traffic flow characteristics 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 mixed automated and manual traffic, to those with fully automated traffic lanes that are physically isolated from manual lanes. The controversial class is where automated vehicles are allowed to mix with manually driven vehicles. The motivation behind this concept is that the current roadway will not have to undergo any major changes. Vehicles will become more and more automated independent of AHS and should have the ability to operate in lanes with manually driven vehicles. As the number of automated vehicles increases, the benefits of automation will increase until saturation, where all vehicles will be automated in the same way with cruise control, air-bags, etc. The purpose of this report is to investigate the requirements, safety issues and throughput that will result from the mixing of fully automated vehicles with manually driven vehicles on the existing roadway system. Two scenarios are considered: scenario I has the fully automated vehicles mixing with the manually driven vehicles on the existing roadway system. In scenario II the roadway controls the traffic flow by communicating with the fully automated vehicles via a roadway/vehicle communication system and with the manually driven vehicles through variable message signs. ________________________________________________________________________ *This work is supported by the California Department of Transportation through PATH of the University of California. The contents of this paper reflect the views of the authors who are responsible for the facts and accuracy of the data presented herein. The contents do not necessarily reflect the official views or