Crowd psychology and engineering

This paper argues that a comprehensive approach to crowd safety design, management and risk assessment needs to integrate psychology and engineering frames of reference. Psychology and engineering are characteristically mutually exclusive in their focus on the perspective of crowd members who think and behave (psychology) or on static and dynamic objects (engineering). Engineering places as much emphasis on the physical environment as psychology negates the relationship between the physical environment and people. This paper stresses the need to address the relationship between (A) design and engineering X (B) communications technology X (C) crowd management X (D) crowd behaviour and movement. Theories of crowd psychology are briefly reviewed with particular reference to crowd ingress and egress and misconceptions about 'panic' or irrational behaviour. Assumptions about panic reinforce an emphasis on the control of a crowd, as if a crowd is a homogeneous mass of bodies or 'ballbearings', rather than the management of a crowd as a collection of individuals and social groups who need accurate and timely information if they are to remain safe. Particular emphasis is put on the fact that the time for a crowd to escape from a situation of potential entrapment is a function of T (Time to escape) = t(1) (time to start to move) + t(2) (time to move to and pass through exits), rather than T = t(2). This is illustrated by reference to research of escape behaviour in the Summerland fire and underground station evacuations. The paper concludes by stressing the need to validate computer simulations of crowd movement and escape behaviour against psychological as well as engineering criteria.