Abstract: Applying the correlation analysis method,the author presents a brief and valid algorithm to identify the pulse response function of a road section,which uses the natural stochastic signals in measureddata of traffic volume on the section. Based on the pulse response function,a new algorithm to estimate themean speed Of vehicles in the section during a long time interval for light traffic conditions is also presented. Moreover,an algorithm to identify the mean effective vehicles length is put forward. The merits of these algorithms are that they do not need to measure the speed of each vehicle and the double-loop detector shouldnot be required.