Abstract: Because of the influence of traffic control signals,speed detected by the downstream loop detectors can not be used to estimate road travel time.To solve this problem,based on the dynamic behavior of vehicles nearby the stop line,this paper analyses the downstream detected speed and modifies it by Newton motion law,and it discusses the different characteristics of vehicle speed between the head of the queue and the others,and estimates the travel time in different parts of the road section,respectively.The authors conducts an experiment using simulation software of VISSIM4.20,to analyses and compare the experimental results estimated based on upstream and downstream loop detectors.Compared with the estimated result based on upstream loop detectors,the result shows that the proposed method can improve the accuracy and stability of experimental results.