Visitor flow modelling in historic buildings

Visitor flow modelling in historic buildings
In restricted space settings, access, circulation and egress affect the mobility of individuals. Historic buildings are a prime example, as they were usually designed for defence and not mass visitation, and their archaic layout, narrow passageways and steep staircases hamper mobility.
Access and egress management is vitally important when considering both the visitor experience and evacuation requirements in an emergency.
Funding Body
Award Value
Start Date
End Date
Duration
Funding Body
Historic Environment Scotland
Award Value
£46,000
Start Date
Apr 16
End Date
Dec 18
Duration
20 months

In restricted space settings, access, circulation and egress affect the mobility of individuals.  Historic buildings are a prime example, as they were usually designed for defence and not mass visitation, and their archaic layout, narrow passageways and steep staircases hamper mobility.  This makes access and egress management important when considering both the visitor experience and evacuation requirements in an emergency. This study has cast light on both factors, using a combination of direct observation, interview, focus group and analysis of 3D scans of two contrasting historic sites: Orkney’s Maeshowe chambered cairn, and Edinburgh Castle Palace. 

Specialist software was used to model the environment and visitor pathways. At Maeshowe where overtaking is infeasible due to the restricted space, directly observed data was used to construct a digital model using the Unity gaming platform, with randomly positioned animated characters scaled to the size and shape of the Scottish population. The field-observed 11-fold difference in egress speed between able-bodied and mobility impaired individuals, together with literature evidence for heavier individuals moving more slowly were input into the model which calculated egress rate and time-to-safety for 20 individuals.  Multiple trials of the model revealed 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 separation between individuals (simulating an emergency) by 26%. Using a size-specific speed model (for characters of 50th, 95th, and 99th percentiles) increased time to safety in emergency evacuation by 51% compared with able-bodied individuals. 

The study concluded that while larger individuals may slow egress times of a group, a single slow-moving mobility-impaired person exerts a greater influence on group egress, adversely affecting those behind. This highlighted that, within historic buildings, restricted width or unidirectional routes are vulnerable to slow moving visitors during egress, who substantially increase the time to reach safety. This criticality of person-order was replicated in a virtual model capable of generating accurate data, which can be scaled to larger and more complex buildings. 

The project also investigated the 3D digital visualisation of built heritage (“viewed from the inside out”), and a focus group and subsequent analysis indicated it’s potential to inform building management practice.  Going forwards, safety and user experience will be combined in further site visits to other selected historic buildings.