Discussion of “Impact Stops on Vehicle Fuel Consumption and Emissions” by Hesham Rakha and Yonglian Ding

Abstract

A discussion of an article with the aforementioned title, published in this journal (Vol. 129, No. 1, January/February 2003), is presented. The discusser recognizes the effort of the author to systematically quantify the impact of vehicle stops and their associated levels of acceleration and deceleration on vehicle fuel consumption and emission rates. However, the discusser argues that a study using only instantaneous speed and acceleration levels as the input parameters has very limited field application. The discusser suggests several points that would have made the study more useful, including the consideration of: engine speed, feasible acceleration rate, differences between emissions from diesel and gasoline engines, roadway-related factors, and the variability of time spent on accelerating and decelerating.