Safety in Numbers? Modelling Crowds and Designing Control for the Notting Hill Carnival

Events such as carnivals, parades, rock concerts, football matches, some types of shopping-indeed, any situation involving rapid exit or entrance from or to high-capacity buildings and vehicles—pose significant problems of public safety. Models designed to predict crowding at such events are in their infancy and the best so far simulate panic situations and evacuation possibilities within buildings and similarly confined spaces. In carnivals and street parades, movement is over a much wider area and crowds form as much through competition between attractions as through confinement in small spaces. A model is proposed in which the event space is first explored by agents using 'swarm intelligence'. Armed with information about the space, agents then move in an unobstructed fashion to the event. Congestion is slowly reduced by introducing controls until a 'safe solution' is reached. The latter stages of the simulation require intervention by those who manage the event, the police. The model has been developed to simulate the effect of changing the route of the Notting Hill Carnival, an annual event held over two days in August each year in a 3 sq km area of west central London. The event attracts over 1 million visitors and is widely regarded as posing a major threat to public safety.