The Effect of Person Order on Egress Time: A Simulation Model of Evacuation From a Neolithic Visitor Attraction.

Abstract

The aim of this study was to model the egress of visitors from a Neolithic visitor attraction. Tourism attracts increasing numbers of elderly and mobility-impaired visitors to our built-environment heritage sites. Some such sites have very limited and awkward access, were not designed for mass visitation, and may not be modifiable to facilitate disabled access. As a result, emergency evacuation planning must take cognizance of robust information, and in this study we aimed to establish the effect of visitor position on egress. Direct observation of three tours at Maeshowe, Orkney, informed typical time of able-bodied individuals and a mobility-impaired person through the 10-m access tunnel. This observation informed the design of egress and evacuation models running on the Unity gaming platform. A slow-moving person at the observed speed typically increased time to safety of 20 people by 170% and reduced the advantage offered by closer tunnel separation by 26%. Using speeds for size-specific characters of 50th, 95th, and 99th percentiles increased time to safety in emergency evacuation by 51% compared with able-bodied individuals. Larger individuals may slow egress times of a group; however, a single slow-moving mobility-impaired person exerts a greater influence on group egress, profoundly influencing those behind. Unidirectional routes in historic buildings and other visitor attractions are vulnerable to slow-moving visitors during egress. The model presented in this study is scalable, is applicable to other buildings, and can be used as part of a risk assessment and emergency evacuation plan in future work.