Carbon dioxide emission of human activities has contributed greatly to the ever increasing of its amount in the atmosphere, which has been proved to be of great influence upon radical climate changes that has incurred many climate disasters, such as unprecedented dry weathers, long-lasting heavy rains and catastrophic snow storms. Automobiles for daily transportation of the mass are one of the major sources of carbon dioxide. With increased average income and lower prices of cars, automobiles have become ordinary traffic tools for common Chinese, which is especially true for downtown areas of counties, where public transportation is not sufficient and usually provides a much lower level of service, compared with similar areas of metropolitans. As a result, automobiles on the streets of Chinese counties are now emitting more and more carbon dioxide than ever before. For efficient control of carbon dioxide emission of motorized vehicles on the streets of Chinese counties, the paper has studied various factors such as characteristics of drivers’ behaviors, vehicle length, traffic volume and street segment length based upon microscopic traffic simulations. It has been found out that traffic volumes have direct connections with average speeds of automobiles, which have great influence upon carbon dioxide emission. Longer street segments have been proved to be more helpful for lower emission of carbon dioxide. Besides, drivers’ behaviors are connected with free flow speeds of vehicles, which have been proved to be an important factor of carbon dioxide emission of automobiles. On the other hand, various vehicle lengths have been found to bring about very little differences to carbon dioxide emission of automobiles. Results of the study can be used to guide traffic planning, management and control. Keywords: carbon dioxide; emission; automobiles; streets; traffic simulation

CICTP