Urban Expressway Lane Speed Limit Theory Research

To formulate a reasonable method of urban freeway speed limits is an important task for better providing transport services to the community, improving security and playing efficiency of the urban freeway. In this paper, through our investigation for China’s urban freeway, we found that China’s urban freeway speed limits settings was lack of theoretical research, no unified theoretical approaches and regulatory measures, as well as existing unreasonable speed limits and other problems. According to the current situations and existing problems of China’s urban freeway speed limits, combining with the results of research of domestic and international speed limit on urban freeway speed limit measures, a systematic study on the China’s urban freeway speed limit measures was conducted and the research was as follows::On the basis of the traffic survey, the speed distribution of the characteristics of law and the relationship between speed and traffic safety under different models was analyzed, different lanes by using the application of statistical analysis, regression analysis of the methodology. It was found that the inside of the urban freeway lane speed was generally higher than the outside lane, the inside lane speed discrete than the outside lane.The urban freeway speed limits standard of divided lane was also studied, sub-models and analyized the relationship between the15%of the bit speed,25%of the bit speed,85%of the bit speed and the velocity standard deviation and the speed limit. Then the appropriateas the minimum, maximum speed limit of the reference value percentile speed of the large and small cars were determined.Two models were established. One was about the relationship between proportion of speeding vehicles and V85with speed limits. The other was about the relationship between the running speed and the degree of dispersion of the running speed. A method for determining the minimum, maximum speed limits standard when sub-lane, divided the models speed limit was proposed. The scope of each lane speed limit through case studies and cluster analysis methods was divided. Finally the simulation by VISSIM simulation software was carried out.After implementing measure sub-lane, the models speed limit was divided. Indicators between the simulation results and not implemented the sub-lane speed limit were compared. It was shown that road capacity, the average speed has been increased and velocity standard deviation significantly has been reduced after the implementation of reasonable sub-lane speed limit.