Elise Miller-Hooks

Publications: Conference 07

“Phased Evacuation in High Rise Buildings: Regulatory Effectiveness Analysis”

International Congress on Fire Safety in Tall Buildings, Santander, Spain.
Brannigan, V. and E. Miller-Hooks (2006)

Phased evacuation involves the dynamic control of people threatened by a hazardous condition and is used instead of providing sufficient exits for a general evacuation. Phased evacuation of buildings, cities or other areas exposed to hazards requires identification of areas in need of early evacuation and a system for moving or directing people to a place of safety. In all cases, the claimed ability to stop, start and control exiting behavior is what distinguishes phased from general evacuation. In high rise buildings, architects, developers and structural and fire engineers have assumed that the structures could meet legal requirements for “safety” by using phased evacuation.

Disasters such as KATRINA and the World Trade Center have exposed some of the comfortable assumptions that underlay the regulatory acceptance of phased evacuation. Individuals simply did not respond as anticipated and control and exiting systems were shown to be inadequate. Since phased evacuation involves human factors and social controls, it is not always easily analyzed using traditional engineering methodologies. In particular, phased evacuation models depend heavily on assumptions that are ethically and technically difficult to test under realistic conditions and are routinely buried deep in the mathematical and computer-based models used to assess evacuation plans.

Regulatory Effectiveness Analysis (REA) provides a methodology for simultaneously analyzing the regulatory system and the related technical tools in carrying out a defined public policy. The regulatory system and the technical tools have interlocking sets of requirements and capabilities. As information flows across the interface between and among various professions, it is critical to accurately characterize and propagate the level and types of uncertainty related to the data and models. It is crucial that the mathematical and computer-based models
used to support phased evacuation explicitly consider the random nature of conditions that affect, for example, the spread of fire, trajectory of a plume of smoke or decision to take a particular exit.

Assumptions made in these models will affect the accuracy of their predictions regarding the performance of a particular building design in an evacuation. By explicitly considering the assumptions embedded in the models in taking decisions related to the predicted performance of a building in an evacuation, discontinuities between regulations and assessments by engineers of a building’s performance can be avoided. As the values assigned within the models to key variables approach the extremes of their range of validity, our confidence in the validity of the model may be reduced.

The special problem of validation or verification of proprietary or unpublished software used to evaluate evacuation plans will be examined in the regulatory context. By establishing “principles” in both engineering and regulation all parties can increase the confidence they have in the use of such software and their embedded models.


Elise Miller-Hooks, Ph.D.
Bill & Eleanor Hazel Chair in Infrastructure Engineering

Phone: 703.993.1685
Email: miller@gmu.edu

Office: 4614 Nguyen Engineering Building

Sid and Reva Dewberry Department of Civil, Environmental and Infrastructure Engineering
George Mason University
4400 University Drive, MS 6C1
Fairfax, VA 22030



Volgenau School of Engineering
George Mason University