CHARACTERISTICS OF VSP DISTRIBUTIONS OF LIGHT-DUTY AND HEAVY-DUTY VEHICLES ON FREEWAY: A CASE STUDY

摘要

Vehicle Specific Power (VSP) has become an essential parameter in the measurementsof vehicle fuel consumption and emissions. In the existing fuel consumption andemission models such as MOVES and IVE, the fuel consumption and emissions arecalculated by a combination of VSP distributions and fuel consumption or emissionsrates. In the conventional transportation model or the traffic monitoring or datacollection system, the spot average travel speed during a particular time interval (i.e.1-min, 2-min, 10-min, etc.) is always used to characterize the traffic performance andvehicle activities. To associate the traffic performance with fuel consumption andemissions, the relationship between VSP distributions of Light-Duty Vehicles (LDVs)and the average travel speed on the urban road has been constructed in earlier studies.This paper focuses on the study of such relationship for Heavy-Duty Vehicles (HDVs)and LDVs on the freeway using a case study. After collecting and processing the fielddata of two case study vehicles, the VSP distribution model on the freeway isdeveloped. Then, a comparison of VSP distributions for LDVs vs. HDVs is conducted,and their regularities on freeway vs. urban road are analyzed. Further, errors inestimating HDV fuel consumption using VSP distributions of LDVs are estimated.Finally, VSP distributions derived from MOEVS are compared with those from thereal-world test and the proposed model. Some similarities are observed in the VSPdistribution pattern for HDVs in China and that derived from MOVES drivingschedules.