Summary: The aim of this paper is to solve the shortcomings that the Pacey’s platoon dispersion model cannot well reflect partial normal distribution in the field situation, a platoon dispersion model based on a truncated lognormal distribution is presented by assuming that the speed follows the truncated lognormal distribution ranging from the minimum to the maximum. The research objects are the temporal and spatial distribution characteristics of queuing vehicles at the upstream intersection after the platoon moves from an upstream at green phase end time. From the density view, the effect of the speed statistical characteristics of these vehicles on the spread of cars along the downstream road is analyzed, and some formulas for calculating traffic flow parameters such as platoon density are presented. Then, the dispersion models of the front and the rear of the platoon are derived to provide traffic data for signal timing plans of the downstream intersection. Finally, by taking the coordination of successive signals for example, the computing traffic flow parameters of the proposed model are compared with those of the Pacey’s platoon dispersion model. The results of numerical simulation show that the former has less advanced and delayed time in optimizing signal timing plans.