  In the event of a fire emergency in the built environment, occupants face a
range of evacuation decisions, including the choice of exits. An important
question from the standpoint of evacuation safety is how evacuees make these
choices and what factors affect their choices. Understanding how humans weigh
these (often) competing factors is essential knowledge for evacuation planning
and safe design. Here, we use immersive Virtual Reality (VR) experiments to
investigate, in controlled settings, how these trade-offs are made using
empirical data and econometric choice models. In each VR scenario, participants
are confronted with trade-offs between choosing exits that are familiar to
them, exits that are less occupied, exits that are nearer to them and exits to
which visibility is less affected by fire smoke. The marginal role of these
competing factors on their decisions is quantified in a discrete choice model.
Post-experiment questionnaires also determine factors such as their perceived
realism and emotion evoked by the VR evacuation experience. Results indicate
that none of the investigated factors dominated the others in terms of their
influence on exit choices. The participants exhibited patterns of
multi-attribute conjoint decision-making, consistent with the recent findings
in the literature. While lack of familiarity and the presence of smoke both
negatively affected the desirability of an exit to evacuees, neither solely
determined exit choice. It was also observed that prioritisation of the said
factors by participants changed during the repeated scenarios when compared to
the first scenario that they experienced. Results have implications for both
fire safety designs and future VR evacuation experiment designs. These
empirical models can also be employed as input in computer simulations of
building evacuation.

Human-Computer Interaction