Jason D. Averill

Pedestrian and evacuation dynamics

Preface.- Dedication.- Pedestrian and Evacuation Dynamics Awards.- Five Grand Challenges in Pedestrian and Evacuation Dynamics.- Data Collection (Evacuation).- Data Collection (Pedestrian).- Data Collection (Vulnerable Groups).- Data Collection (Transport).- Data Collection Methods.- Theory for Models.- General Model Development.- Large-scale Modeling.- Transport Modeling.- Modeling Methods.- Model Calibration / Validation.- Vertical Egress.- Regulations / Engineering Guidance.- Posters

Stairwell Evacuation from Buildings: What We Know We Don’t Know

Occupant descent down stairwells during building evacuations is typically described by measurable engineering variables such as stairwell geometry, speed, density, and pre-evacuation delay. In turn, predictive models of building evacuation use these variables to predict the performance of egress systems for building design, emergency planning, or event reconstruction. This paper provides a summary of literature values for movement speeds and compares these to several new fire drill evacuations. Movement speeds in the current study are observed to be quite similar to the range of literature values. Perhaps most importantly though, the typical engineering parameters are seen to explain only a small fraction of the observed variance in occupant movement speeds. This suggests that traditional measures form an incomplete theory of people movement in stairs. Additional research to better understand the physiological and behavioral aspects of the evacuation process and the difference between fire drill evacuations and real fire emergencies are needed.

Five Grand Challenges in Pedestrian and Evacuation Dynamics

This paper identifies five grand challenges in the multidisciplinary field of pedestrian and evacuation dynamics (PED). In order to maximize the effectiveness of limited resources, the PED community would benefit greatly from a prioritized, consensus-based research agenda. The five proposed research initiatives include (1) a general human behavior model with a theoretical foundation and numerical validity, (2) a database archiving actual building emergency evacuations, (3) methods to embrace the stochastic nature of inputs and outcomes in building evacuation, (4) a validated method to integrate distributions of egress calculations with fire hazard calculations, and (5) adoption of technology for people movement, data collection, and within modeling constructs. The list proffered in this paper may reflect the building evacuation perspective of the author and is intended merely as a spark for discussion amongst the greater PED community; a true consensus research agenda requires deliberation by leaders in the community.

Movement on Stairs During Building Evacuations

The time that it takes an occupant population to reach safety when descending a stair during building evacuations is typically estimated by measureable engineering variables such as stair geometry, speed, stair density, and pre-observation delay. In turn, engineering models of building evacuation use these variables to predict the performance of egress systems for building design, emergency planning, or event reconstruction. As part of a program to better understand occupant movement and behavior during building emergencies, the Engineering Laboratory at the National Institute of Standards and Technology (NIST) has been collecting stair movement data during fire drill evacuations of office and residential buildings. These data collections are intended to provide a better understanding of this principal building egress feature and develop a technical foundation for future codes and standards requirements. NIST has collected fire drill evacuation data in 14 buildings (11 office buildings and 3 residential buildings) ranging from six to 62 stories in height that have included a range of stair widths and occupant densities. A total of more than 22000 individual measurements are included in the data set. This report provides details of the data collected, an analysis of the data, and examples of the use of the data. The intention is to better understand movement during stair evacuations and provide data to test the predictive capability of building egress models. While mean movement speeds in the current study of 0.44 m/s ± 0.19 m/s are observed to be quite similar to the range of values in previous studies, mean local movement speeds as occupants traverse down the stairs are seen to vary widely within a given stair, ranging from 0.10 m/s ± 0.008 m/s to 1.7 m/s ± 0.13 m/s. These data provide confirmation of the adequacy of existing literature values typically used for occupant movement speeds and provide updated data for use in egress modeling or other engineering calculations. (Less)

Characteristics of Fire Scenarios in Which Sublethal Effects of Smoke are Important

A number of simulations were performed using the CFAST zone fire model to predict the relative times at which smoke inhalation and heat exposure would result in incapacitation. Fires in three building types were modeled: a ranch house, a hotel, and an office building. Gas species yields and rates of heat release for these design fires were derived from a review of real-scale fire test data. The incapacitation equations were taken from draft 14 of ISO document 13571. Sublethal effects of smoke were deemed important when incapacitation from smoke inhalation occurred before harm from thermal effects occurred. Real-scale HCl yield data were incorporated as available; the modeling indicated that the yield would need to be 5 to 10 times higher for incapacitation from HCl to precede incapacitation from narcotic gases, including CO CO2, HCN and reduce O2.The results suggest that occupancies in which sublethal effects from open fires could affect escape and survival include multi-room residences, medical facilities, schools, and correctional facilities. In addition, fires originating in concealed spaces in any occupancy pose such a threat. Sublethal effects of smoke are not likely to be of prime concern for open fires in single- or two-compartment occupancies (e.g., small apartments and transportation vehicles) themselves, although sublethal effects may be important in adjacent spaces; buildings with high ceilings and large rooms (e.g., warehouses, mercantile); and occupancies in which fires will be detected promptly and from which escape or rescue will occur within a few minutes.

Federal Investigation of the Evacuation of the World Trade Center on September 11, 2001.

This paper presents the findings of the NIST World Trade Center Investigation describing the occupant evacuation of WTC 1 and WTC 2 on September 11, 2001. The egress system, including stairwells and elevators, is described along with the evacuation procedures. The population in WTC 1 and WTC 2 on September 11, 2001 at 8:46 a.m. is enumerated and described, where the background of the population was relevant to the subsequent evacuation, including training, experience, mobility status, among others. The progress of the evacuation of both towers is described in a quasi-chronological manner. A decedent analysis explores where occupants were located when each tower was attacked. Multiple regression models were built to explore the sources of evacuation initiation delay (why people did not immediately start to leave the building), as well as stairwell evacuation time (how long the average occupant spent in the stairwells per floor). Issues identified as contributing to either slowing or aiding the evacuation process were explored. Egress simulations provided context for estimating how long WTC 1 and WTC 2 would have taken to evacuate with different populations, using three different models, and subject to different assumptions of damage to the building.

Sensitivity of a Smoke Toxicity Test Method to Test Conditions

Experiments have been conducted in the NFPA 269 / ASTM E1678 radiant apparatus to determine the sensitivity of toxic gas generation to atmospheric oxygen availability and to the conformation of the test specimen. CO and HCN generation can be dependent on the conformation of the test specimen. Thus, it is important that the test specimen exposure to the radiant source adhere to the likely real-fire exposure of the finished goods. Reducing the initial oxygen volume fraction in the apparatus can affect CO and HCN generation, but does not appear to affect the HCl generation. Fitting the bench-scale test conditions to the full-scale fire ventilation conditions is likely to be important in obtaining good correlations of toxic gas generation.