The Influence of Stops on Vehicle Fuel Consumption in Urban Traffic

A simple linear relation between fuel consumption per unit distance, (phi) and trip time per unit distance T , (phi) = k 1 + k 2 T is established for the fuel data collected in Austin and Dallas, Texas, and Matamoros, Mexico. The qualities of traffic service in these cities are compared through the study of the spread of the data points along the (phi), T trend, showing that the Matamoros data in general have higher (phi) and T values. The fuel consumption model (phi) = k 1 + k 2 T is improved by the addition of a term proportional to (Delta) N s ( T ), the deviation of the number of stops for a given datum point from the average number of stops associated with the trip time interval into which the datum point falls. It is shown in the resulting new model, (phi) = k 1 + k 2 T + k 3 (Delta) N s , that since T and (Delta) N s are virtually uncorrected, the values of k 1 and k 2 in the simpler model remain unchanged. A discussion of the physical interpretation of the model parameters is presented. In addition, an analysis of data obtained in central London shows that k 1 depends almost entirely on vehicle mass. It is also shown that the value of the parameter k 3 is approximately given by the product of the warmed-up idle fuel flow and the average stop duration.