This article describes the results of a large-scale survey of the operating characteristics of cars used in urban areas. Privately owned cars are instrumented to measure and continuously record a wide range of variables defining the operation of the engines and vehicles while they are used by their owners. The measurements are made on a total of 14 car models, in two cities in each of three European countries, and the data provide information on the actual use of cars for a wide cross-section of normal European driving. At this point of the experiment, 36 of the 60 cars have been tested, giving a record of 5500 trips, covering a total distance of 44,000 kilometres. On this partial basis, vehicle use and running conditions are analyzed: characteristics of the trips, frequency of vehicle use, vehicle speeds. In order to characterize driving and traffic conditions, statistical factorial analyses of the speed curve of the vehicle as a function of the time are done. The analysis method - currently in progress - is described. The results show that it is possible to characterize traffic conditions through the analysis of the speed and acceleration profiles, and to identify the different classes of relatively homogeneous traffic conditions. A set of representative driving cycles will be derived from these data to typify the observed driving patterns, taking into account, where it will be found to be significant, the influence of the vehicle type, the driver, and the location as well as the detailed records of engine operations. It is intended to conduct an extensive series of emission tests, using these realistic driving cycles, and to develop detailed and accurate models of exhaust emission rates in terms of urban driving behaviour. As an interim measure, in advance of the availability of comprehensive information, an analysis is presented using published data on exhaust emissions. Preliminaries to the emission measurements are described.
Abstract