A Review of Building Evacuation Models - NIST Virtual Library

A.16 Myriad
Developer: G.K. Still, Crowd Dynamics, Ltd, UK
Purpose of the model: The purpose of this model is to assess the spatial dynamics required for
a successful evacuation 73, 74 . Myriad is also used to ensure compliance to codes and insurance
assessment. This is a macroscopic model, and because of this, Still states that the output does
not depend on assumptions about the population incorporated in the model. This collection of
techniques supersedes the VEgAS and Legion systems.
Availability to the public for use: This model is used by Crowd Dynamics for the client.
Ideas and Applications: Myriad 73 is said to predict where congestion will occur in the building
and its severity (via Level of Service 60 degrees), flow rates, queues, travel distances, and times in
order to “optimize” design. The developer 74 identified three basic steps used in the analysis
process using Myriad. First, Myriad measures the distance, width, ease of use, and directional
changes from all points within the building space to the exits. This is the analysis that ensures
compliance to the codes. Colors throughout the building’s egress routes are used to show
evacuation aspects of the building, for instance, travel distance of various distances. The
building can be assessed with and without furniture, which can ultimately affect travel distances
from certain areas of the space. The occupant can enter the number of occupants within the
building/space and Myriad will produce simulations, each beginning occupants at different
places, in order to test building travel distances.
Second, Myriad identifies the various flow paths, interaction paths, and congestion areas.
These are ultimately factored into the “delays” in the egress process. The interactions and
congestion paths within the model are also identified by certain colors throughout the building in
this analysis. Tables A.8 – A.11 below show the corresponding colors for each Level of Service
(taken from Fruin’s data 60 ) for each building components (walkways, stairs, queues, and
platforms). The visualization software allows the client to view the density of the spaces in the
building throughout the simulation. As another example of the capabilities of Myriad, through
the use of hesitation maps, Myriad can highlight areas where occupants may hesitate, change
routes, or require more information to direct them to a destination.
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