Dependence of Modelled Evacuation Times on Key Parameters and Interactions

Times and patterns of buildings evacuations involve interactions between many behavioural parameters reflected in the increasing complexity of computer simulations. A combination of detailed GridFlow computer evacuations simulations, calculation models and experimental evacuations have been used to determine the extent to which evacuation patterns and times are largely dependent upon a small number of key parameters and interactions. Cases investigated included a single retail enclosure and multi-enclosure, multi-storey office buildings designed following UK prescriptive guidance. It is concluded that evacuation times are very dependent upon a small number of critical factors (including PTAT distributions, exit choice ratios, maximum flow rates, merge ratios, and densities of stationary and moving groups), and that even the most sophisticated computer simulations can give misleading results if these factors are not adequately represented. It is considered that simple calculation methods can provide a useful first estimate of evacuation times for designers, and a useful check on the performance of more complex simulation models.