摘要：Speed regulation of motor vehicles has widely affected the living environment and standard of residents in urban areas. It is believed that lower speed of motor vehicles could decrease the traffic accident rate on roads. However, lower speeds may cause many problems indirectly to social development and the health of residents. The average speed of motor vehicles in urban areas in China may be among the lowest in the world due to its mixed traffic environment and vehicle properties. In most central areas of large Chinese cities, the average speed of motor vehicles has been lower than 25km/h. However, this does not mean a safer system for transportation. For example, the death toll of transportation systems in China has exceeded 70,000 every year and is among the highest in the world. This paper analyses the general situation of various speed regulations on motor vehicles in China. A brief review on the relationship between speed and safety on urban transport has been described. Authors believe that the most important factor to menace transport safety is the coordination of motor vehicles with bicycles and pedestrians especially in urban areas. A quantitative assessment on indirect effects of speed regulation has then been discussed. The assessment covers four aspects. Firstly, it estimates the additional emissions resulted from speed regulation. Secondly, it calculates the contribution to road traffic density of extra stay of vehicles caused by speed change. Thirdly, it analyses the change of passenger journey time caused by speed regulation in urban areas. Finally, the paper calculates the energy consumption of vehicles related to speed regulation. The paper also discusses the policy on speed regulation from viewpoint of sustainable development of urban society. It concludes that higher speed of motor vehicles is of better sustainability in the current situation of Chinese urban areas. Some suggestions on speed regulation for different situations in China have also been presented. The research has been part of the project funded by the Natural Science Foundation of China (No. 70173014) and the Royal Society of UK.
关键词：Speed regulation ; Transport sustainability ; Road carrying capacity
