The traditional method of signal coordination is only based on the average speed of platoon vehicles. This method fails to consider the actual characteristics of the platoon and therefore may not yield optimum coordination results. The characteristics of the platoon is reflected by platoon variables, such as headways or vehicle speeds. In order to take the true characteristics of the platoon into account, a new method that considers the distribution of the platoon variables is proposed in this paper. First, actual traffic data are collected. Distribution studies are conducted based on these data and then compared with normal distribution. The generalized extreme value distribution is found to better fit the platoon data, particularly at both ends. New offset strategies based on different distribution characteristics from the generalized extreme value distribution are then proposed and used as input of simulation for evaluation along with other offset strategies. The optimum strategy is decided based on the simulation results from CORSIM. The results suggest that the optimum offset strategy should be adjusted based on different factors including link length, degree of saturation and cross street volume. It is also found that the optimal offsets correspond to different distribution percentile values for different conditions.
