The management and control of crowds is crucial to the maintenance of public safety. Since crowd congestion prevents the smooth flow of traffic, possibly creating crammed and potentially unsafe conditions, it is important to closely monitor crowd-congestion conditions, to provide timely data analysis and to evaluate the potential for the development of unsafe conditions. This study proposes a method that uses video-monitoring devices to closely monitor crowd conditions and creates a grid model to efficiently detect crowd congestion and to facilitate the analysis necessary for crowd management.It is expected that the higher the congestion level, the higher is the risk of the development of unsafe conditions, especially in the case of congestion near an exit. This study uses a discrete geometric moment to determine the distribution of the congestion. A linear estimation is used to assess the varying moment, to determine the variation of congestion levels and to evaluate the increase or decrease in congestion levels with time.Based on the variation of congestion levels and the movement of the congestion center, it is possible to predict the future direction of the congestion's movement and its potential impact. The data collected forms the basis for a process for appropriate crowd control or evacuation measures, in order to reduce the risk of crammed and unsafe conditions.