Automotive exhaust emissions were studied from the standpoint of urban traffic conditions. Auto traffic data were obtained in Tokyo, Japan, using a test car monitored for vehicle speed and other pertinent data. Eleven different kinds of traffic patterns in Tokyo were identified which seemed to most closely represent urban driving conditions.
Forty-eight motor vehicles, consisting of 1971 to 1976 model year passenger cars, vans and trucks (gasoline and diesel), were driven on a chassis dynamometer to measure emissions under the eleven patterns mentioned above. The characteristics of NOx, HC and CO emissions and fuel consumption by vehicle type and model year were obtained and correlated with vehicle speeds. By combining these analyses of emissions as a function of vehicle speed with estimated present and expected future traffic data in Tokyo, the total emissions and fuel consumption by vehicles in the Tokyo metropolitan area were estimated. Calculated fuel consumption coincided well with fuel sales data.
It was found that the 10 mode Japanese official test method would underestimate total emissions in an urban area, especially for vehicles certified to meet stringent emission standards.