Optimal Traffic Signal Strategy for Fuel Consumption & Emissions Control at Signalised Intersections



Optimal Traffic Signal Strategy for Fuel Consumption & Emissions Control at Signalised Intersections

Authors

LIAO T-Y and MACHEMEHL R, University of Texas at Austin, USA

Description

Fuel economy is an important issue because of both energy conservation and environmental concerns. Fuel consumption and emissions in ground transportation can be reduced by increasing vehicle standards and optimizing traffic system management. Although th

Abstract

Fuel economy is an important issue because of both energy conservation and environmental concerns. Fuel consumption and emissions in ground transportation can be reduced by increasing vehicle standards and optimizing traffic system management. Although the Corporate Average Fuel Economy Act (CAFE) has propelled fuel economy of new vehicles from 14 miles per gallon per car (mpgpc) to 28 mpgpc in 1992, more than 60% of all vehicles are at least five years old. Due to their design and maintenance needs, these older vehicles consume far more fuel and produce more emissions than the new models and they compose the majority of the vehicle fleet. Therefore, motivated by the Clean Air Act Amendments, the USEPA (U.S. Environmental Protection Agency) has initiated a number of studies to reduce automobile fuel consumption and emissions.

This paper investigates vehicle fuel consumption and emissions at signalized intersections where signal control causes vehicles to slow, stop, and accelerate consuming excess fuel and producing more emissions. Most existing fuel consumption and emissions models for signalized intersections are developed based on instantaneous data, in which vehicle speed-acceleration-deceleration profiles are utilized. However, these models are unable to directly reflect the impact of traffic control measures, such as traffic signal timing on fuel consumption and emissions. Within this study, signal parameters, vehicle characteristics, and geometric conditions of signalized intersections are considered to estimate fuel consumption and emissions. Therefore, traffic signal strategy optimization can be developed through trade-offs of fuel consumption, delay, and other measures of effectiveness.

In Section 2, criteria for signal design are briefly discussed and the trade-offs between fuel consumption and delay are addressed. An Analytical Fuel Consumption Model is described in Section 3. Field tests producing vehicle speed and acceleration/deceleration profiles as well as FTP (Federal Test Procedure) data from the USEPA are combined to calibrate the fuel consumption model. In the numerical experiments, the AFCM and Webster's delay model are used to calculate optimal signal timing on fuel consumption and delay, and the results are compared with those from the TEXAS simulation model.

Publisher

Association for European Transport