Maritime traffic safety and port capacity is increasingly important nowadays. Due to the fast development of vessel traffic in ports and waterways, a lot of attention has been paid to maritime traffic safety and port capacity. Many simulation models have been used to predict traffic safety and port capacity m ports and waterways. However, maritime traffic models only consider few aspects, as the influences of human behavior and external factors have not been included regarding maritime traffic safety. To investigate the vessel behavior and external influencing factors, an analysis has been performed based on Automatic Identification System (AIS) data under various external conditions. The study area includes a junction and a slight bend with high maritime traffic density within the port of Rotterdam, the Netherlands. Vessels are classified m different categories based on their type and gross tonnage. Equidistant cross-sections approximately perpendicular to the navigation direction are used for investigation of vessel behavior, including speed, course and path for each vessel category. The influences of external factors (wind, visibility and current) on vessel behavior are identified by comparmg with unhindered vessel behavior. In the analysis, specific thresholds are set to select external conditions and eliminate the influence of encounters. The analysis of unhindered vessel behavior for each vessel category provides insight into vessel behavior. The results revealed that the wind has influence on vessel path, the visibility can affect vessel speed and path, and the current can influence vessel speed. Analysis results can be used as input for the development of new maritime traffic model, as well as for its verification and validation