To study the characteristics of the dispersion of traffic along the road link, factors affecting the dispersion, and the impact of the diffusion on the performance of traffic. The examination on the dispersion of vehicle platoon was carried out by two means: The distribution of traffic flow and the distribution of travel time. The data were collected on two urban arterials in Bangkok, from the stop line to the 1400-m distance away. The results of the analyses indicated that the Robertson model and the transformed normal distribution well fitted the dispersion of traffic volume and travel time, respectively. The average platoon dispersion factor, K, on two roads were 0.242 and 0.167. The study showed that the dispersion of platoon was correlated with the cycle time, traffic volume, number of motorcycles, percentage of lane changes and road activities. In addition, the dispersion affected the performance of the traffic signal operations