Ember Alerts: Assessing Wireless Emergency Alert (WEA) Messages in Wildfires Using the Warning Response Model

When evacuation is necessary in a wildfire event, affected communities must be alerted and warned of the imminent danger and instructed on what to do to protect themselves. One channel available to message providers in the United States is Wireless Emergency Alerts (WEAs) disseminated via IPAWS. Recent wildfire events have shed light on the need to improve WEA strategies and messages when alerting exposed populations of imminent fire threat. The purpose of this article is to assess how, when and where WEAs have been used in US wildfires; whether they comply with guidance set out by Mileti and Sorensen’s Warning Response Model (WRM); and whether the expansion in characters (from 90 to 360) of WEA messages has influenced compliance with the WRM. A quantitative content analysis was conducted of WEA messages sent during US wildfires from January 2020-April 2022. A total of 1,284 messages were manually coded based upon the content and style categories identified in the WRM. Descriptive analyses (and Chi-square tests) were performed to illustrate how 90-character and 360-character WEA messages differ by key content and style features. Results showed that certain content features (i.e., location, guidance, and the name of the hazard) were included more often than others (i.e., source, hazard description, hazard consequences, and timing information) and that the inclusion of most content features increased with increasing message character length. Additionally, when assessing message ‘completeness’, the use of acronyms was prevalent in both 90- and 360-character wildfire WEAs; whereas the inclusion of URLs was linked to increased message length. Wildfire WEAs also displayed inconsistency both within and across states in their use of terminology to trigger evacuation. These findings, among others, have implications for theory highlighting a growing need to confirm that message receivers understand and can act on the messages sent, regardless of the language used. In addition, for message creators, recommendations for effective WEA messages for wildfires are provided

A review of post-incident studies for wildland-urban interface fires

Abstract Post-incident studies provide direct and valuable information to further the scientific understanding of Wildland-Urban Interface (WUI) fires. Most post-incident studies involve data collection in the field (i.e. a "research field deployment"). In this review, technical reports of post-incident studies for WUI fire and other natural disasters were analyzed and professionals directly involved in WUI fire research field deployments were interviewed. The goal of this review is to provide a resource for future WUI studies regarding the development of safe and effective fieldwork procedures, the collection and integration of accurate and relevant data, and the establishment of practical lessons learned. Three main stages of WUI fire post-incident studies are identified and described in detail. Data collection methodologies, data attributes, logistical practices and lessons-learned were compiled from various past studies and are presented here in the context of application to WUI fire

Roxborough park community wildfire evacuation drill: data collection and model benchmarking

Wildfires are increasing in scale, frequency and longevity, and are affecting new locations as environmental conditions change. This paper presents a dataset collected during a community evacuation drill performed in Roxborough Park, Colorado (USA) in 2019. This is a wildland-urban interface community including approximately 900 homes. Data concerning several aspects of community response were collected through observations and surveys: initial population location, pre-evacuation times, route use, and arrival times at the evacuation assembly point. Data were used as inputs to benchmark two evacuation models that adopt different modelling approaches. The WUI-NITY platform and the Evacuation Management System model were applied across a range of scenarios where assumptions regarding pre-evacuation delays and the routes used were varied according to original data collection methods (and interpretation of the data generated). Results are mostly driven by the assumptions adopted for pre-evacuation time inputs. This is expected in communities with a low number of vehicles present on the road and relatively limited traffic congestion. The analysis enabled the sensitivity of the modelling approaches to different datasets to be explored, given the different modelling approaches adopted. The performance of the models were sensitive to the data employed (derived from either observations or self-reporting) and the evacuation phases addressed in them. This indicates the importance of monitoring the impact of including data in a model rather than simply on the data itself, as data affects models in different ways given the modelling methods employed. The dataset is released in open access and is deemed to be useful for future wildfire evacuation modelling calibration and validation efforts.This study was supported by National Institute of Standards and Technology, U.S. Department of Commerce under award 60NANB18D255. The EMS was developed by the University of Cantabria within the ASSISTANCE project funded by the European Union’s H2020 research and innovation programme under grant agreement No. 832576

What a User should Know when Selecting an Evacuation Model

In recent years, evacuation models have been increasingly applied in an attempt to understand the outcome of emergency egress scenarios

An analysis of evacuation travel paths on stair landings by means of conditional probabilities

This paper analyses data on occupants׳ movement on stair landings collected during an evacuation drill performed in a six-storey office building in the United States. A total of 215 occupant travel path trajectories were filmed and time on the stair landings and egress behaviours were analysed. Data were analysed using a probabilistic approach, i.e., the probability of different occupant travel paths were calculated in relation to two different factors: (1) crowding on the landings, and (2) the type of interactions between occupants (e.g., merging flows, deference/overtaking behaviours, etc.). Results showed that a higher number of occupants on stair landings caused an increase in the probability for (1) longer travel paths and (2) usage of the outer boundaries on the stair/landing connections. This paper highlights that data and modelling assumptions should be used after a careful evaluation of their field of applicability. In the case of a low occupant load and non-homogenous merging streams (a higher number of people entering the landing from the stairs than the door), floors tend to be emptied from the top to the bottom

A probabilistic approach for the analysis of evacuation movement data

This paper presents a probabilistic approach to analyse evacuation movement data. The approach relies on a detailed video analysis of people movement and pattern reconstruction. Conditional probabilities for travel path trajectories, walking speeds, and physical area occupied on stair landings are calculated for the evacuee population. The approach has been applied as a case study using data from an evacuation drill performed in a six-storey office building in the United States. The evacuation drill was filmed and occupant's behaviours on stairs were analysed using the new method. A comparison with the deterministic methods currently employed in engineering practice has been performed. The benefits of the probabilistic approach are discussed, including (1) a more accurate representation of people movement and (2) the use of probabilistic data for modelling purposes, i.e., model validation and model development

The Process of Verification and Validation of Building Fire Evacuation Models

To date, there is no International standard on procedures and tests to assess the verification and validation (V&V) of building fire evacuation models. Often it is the case that model testers adopt inconsistent procedures, or tests designed for other model uses or they do not test them for all features embedded in their model. For instance, the tests presented within the MSC/Circ.1238 (Guidelines for evacuation analysis for new and existing passenger ships) provided by the International Maritime Organization are often employed for the V&V of models outside their original context of use (e.g. building fires instead of maritime applications). This document is intended to open a discussion on the main issues associated with the definition of a standard procedure for the V&V of building fire evacuation models. A review of the current procedures, tests and methods available in the literature to assess the V&V of building evacuation models is provided. The capabilities of building evacuation models are evaluated by studying their five main core components, namely 1) pre-evacuation time, 2) movement and navigation, 3) exit usage, 4) route availability and 5) flow constraints. A set of tests and recommendations about the verification and validation of building evacuation models is proposed. These tests include suggestions on using simple tests of emergent behaviours together with examples of experimental data-sets suitable for the analysis of different core components. The uncertainties associated with evacuation modelling are discussed. In particular, a method for the analysis of behavioural uncertainty (uncertainty due to the use of distributions or stochastic variables to simulate human behaviour in evacuation modelling) is presented. The method consists of a set of convergence criteria based on functional analysis. The last part of this document presents a discussion on the issues associated with the definition of the acceptance criteria of a standard V&V protocol

Assessing the Verification and Validation of Building Fire Evacuation Models

To date there is no International standard on the verification and validation (V&V) of building fire evacuation models, i.e., model testers adopt inconsistent procedures or tests designed for other model uses. For instance, the tests presented within the MSC/Circ.1238 Guidelines for evacuation analysis for new and existing passenger ships provided by the International Maritime Organization are often employed for the V&V of models outside their original context of use (building fires instead of maritime applications). This paper presents a list of verification tests for component testing and the analysis of emergent behaviours together with examples of experimental data-sets suitable for the analysis of different core components. The capabilities of building fire evacuation models are evaluated by studying their five main core components, namely (1) pre-evacuation time, (2) movement and navigation, (3) exit usage, (4) route availability and (5) flow constraints. This paper discusses the tests which are included in a freely available Technical Note developed at the National Institute of Standards and Technology. This work is intended to open a discussion on the main issues associated with the definition of a standard procedure for the V&V of building fire evacuation models, including the definition of the acceptance criteria of a standard V&V protocol