WUI Fire Data Collection and Exposure Modeling Project

Summary:

The Wildland-Urban Interface (WUI) is defined as a location where structures meet or intermingle with undeveloped wildland. Since 2000 in California alone, an average of over one thousand structures per year have been lost to WUI fires. Despite this significant WUI fire problem, there is little information on fire behavior at the WUI. An improved understanding of WUI fire dynamics is critical to assessing and improving current methods of reducing structure ignitions. The objective of this project is to determine fire behavior at the Wildland Urban Interface (WUI) by conducting post fire incident reconnaissance and analysis. Data collected will be used for the development of improved standards and building codes, contributions to the NIST Disaster and Failures Database, planning critical research such as experiments on structural vulnerabilities to WUI fire exposure, and validation of the NIST WUI Fire Dynamics Simulator (WFDS), leading to a first generation methodology for assessing and mitigating risk in WUI communities by the end of 2013.

Description:

Objective: Determine fire behavior at the Wildland Urban Interface (WUI) using post fire analysis and collect data for the development and validation of the NIST WUI Fire Dynamics Simulator (WFDS), leading to a first generation methodology for assessing and mitigating risk in WUI communities by the end of 2013.

What is the new technical idea? The new technical ideas are field data collection efforts in coordination with state and local agencies, the development of standardized data collection methodologies that once implemented will generate reliable post incident data, inclusion of data into NIST’s Disaster and Failure Studies Repository, and the use of the NIST WFDS and targeted lab and field experiments to improve risk assessment and mitigation predictions. Documentation of defensive actions during WUI fire incidents is critical to the understanding of WUI structure survivability and the effectiveness of risk reduction methodologies.

What is the research plan? The Research Plan is developed around two key technical ideas. A framework will be developed for the acquisition of reliable and useful WUI fire incident data. The collected WUI fire data will be used to identify structure ignition vulnerabilities and guide hazard reduction research including specifically exposure modeling. In more detail, the Research Plan will include the following research activities:

Case Studies and Post Incident Data Repository Conduct the Tanglewood Complex fire (Amarillo, TX, 2011) case study and finish the Witch/Guejito case study – findings from these studies will be used to identify structure ignition vulnerabilities and guide hazard reduction research and solutions. The post Witch fire data collection will continue with the support of CALFIRE and the City of San Diego. The State and City have provided access to the site for NIST personnel during and after the fire. The analysis is divided into two components.

The first study focused on The Trails subdivision at Rancho Bernardo. This community of approximately 270 homes was almost entirely within the fire perimeter. Seventy four homes were completely destroyed and sixteen were damaged. The study focused on the development of a timeline for the evolution of fire and structure ignitions throughout the community.

The NFPA Firewise methodology for WUI fire community protection will be applied to The Trails and the validity of the methodology will be assessed. This is possible through extensive data collection conducted during and after the fire. In order to map out the community, NIST, with CALFIRE support, has taken over 11,000 pictures of the destroyed and remaining homes. A database is being developed to house the Witch and Guejito Fire data (including the pictures) collected in 2007 and 2008 (see Post Fire Incident Methodology).

In the second study, an attempt will be made to understand why the fire took certain “paths” though the community and why certain structures burned, while others survived. With input files generated from the Coeur D’Alene extramural project WFDS will provide information on the track of firebrands through the community and the effects of topography on flow dynamics. This step is critical as in order to characterize the effectiveness of Firewise structure treatments, comparisons need to be made of structures that were subjected to similar brand exposures.

Using the lessons learned during the Witch Fire data collection, a methodology is being developed to collect, store and analyze pre and post-WUI fire data. The joint effort between NIST, CALFIRE and the City of San Diego is aimed at standardizing data collection to ensure that critical data is not lost (due to recovery efforts) and that data compatibility is assured. Different hardware, software and field methodologies are assessed, with the aim of creating a California state-wide data collection infrastructure. The data collected at The Trails will be input in the database and analyzed to determine how structure construction and landscaping attributes affected structure fire performance during the Witch Fire. This database will also be used by WFDS to develop case studies and recreate parts of the Witch Fire.

The database is Geographic Information System (GIS) based. The plot and structure particulars collected including damage to vegetation will be included in the database along with the defensive actions documented in the first report. The GIS framework will enable spatial queries of the data. The dynamic framework will allow for expansion of the collection fields if future data collections identify additional features of interest.

A comprehensive post-incident field survey, documenting all the structures within the fire perimeter or a community of interest allows a systematic assessment of structure ignition vulnerabilities. Documenting only destroyed and damaged structures can result in erroneous assessments and misleading conclusions with respect to structural vulnerability.^[1] Data collected from NIST WUI Fire deployments will be integrated into the NIST Disaster and Failure Studies Repository.

The NIST WUI data collection methodology was used to train the Texas Forest Service in October 2010 and was field tested during the initial reconnaissance deployment in response to the fires around Amarillo, Texas in February 2011.

The National WUI Fire Data Collection Team The NIST WUI data collection efforts to date (Witch 2007 and Tanglewood Complex 2011) were accomplished through partnerships with CA and TX. While this model had been proved successful a national framework is necessary in order to respond to WUI incidents in other states. The development of a National Fire Data Collection Team will be developed in partnership with the US Forest Service. The National Team will enable access to fires in all states. The utilization of highly trained personnel, together with the developed QA/QC plan, will ensure data reliability. The National WUI Fire Data Collection Team will be used to collect detailed WUI community fire response data.

A technical partnership has been developed with the USFS Fire Engineering Research Applications (FERA) Team. The new technical ideas associated with this partnership are:

To develop a national WUI post-fire data collection team. The partnership with the USFS will enable access to WUI fire incidents at a national level. This is in contrast to the state-centric approach used to date between NIST, CA and TX.
Use the FERA fuels expertise to capture the exposure from the wildlands to the community. The NIST built environment expertise will be augmented by the USFS wildland and residential vegetative fuels expertise. The exposure from vegetative fuels in the wildlands is the missing link in characterizing the threat to structures in a community. Exposure information will be used to develop the foundation for a national WUI fire exposure or intensity scale.
Information sharing on field wind data, which will assist with WFDS model validation and help characterize WUI fire exposure severity.

Wide spread use of NIST developed WUI data collection methodology To date there has been no standardized approach to collect basic WUI community fire response data at a national level. The NIST WUI 1 data collection methodology had been designed to address this need. The widespread use of the NIST developed WUI 1 data collection methodology will generate a usable data set of what structures are burning in the WUI. This information will be used to guide the National WUI Fire Data Collection Team deployments. Data collected from WUI Fire deployments by trained personnel will be integrated into the NIST Disaster and Failure Studies Repository.

Develop a WUI Exposure Scale – concept development There is a critical lack of quantitative information on the assault on structures from embers and fire. This is only in part due to the lack of a common scale for quantifying this exposure. An exposure scale can be used to successfully improve the building codes and standards as well as the building practices to meet the survivability requirements of structures in certain fire and ember exposure environments.

Unlike a hurricane that gets an overall rating based on maximum sustained winds, a WUI fire, being so dynamic and variable in space and time will not get a single rating. The framework for a WUI exposure scale will be developed and used to guide current and future WUI research as well as developments in codes, standards and best practices.

WFDS simulation of WUI wind Wind, topography and fuels are the main attributes that affect WUI fire behavior. The presence of severe winds such as the Santa Anna’s or the winds seen in the Texas pan handle can produce extreme fire behavior. The focus of this effort will be in developing wind predictive capabilities. This will be accomplished through coupled experimental and modeling work at parcel, community and landscape scales. This will be done in collaboration with the Green House Gas Emissions and Transport Project (PI: Prasad). Collaborators include NOAA, the National Center for Atmospheric Research (NCAR) and the US Forest Service.

Technology transfer Technology transfer will be accomplished on the framework developed by the WUI exposure scale. Specifically the WUI exposure scale will enable the codes, standards and best practices to reflect the hazard reduction requirements associated with specific exposure conditions. Cost effective solutions will be enabled both for new construction as well as retrofit by building to meet specific WUI exposure requirements. Technical partnerships have been developed with key stakeholders from Codes and Standards organizations to key state agencies to enable this technology transfer.

Major Accomplishments:

Recent Results:

Output: Draft NIST TN Report, “Initial Reconnaissance Report on Initial Reconnaissance of the 2011 Wildland-Urban Interfaces Fires in Amarillo, Texas.”
Numerous invited presentations on WUI data collection methodology and Witch/Guejito Case Study.^[2]
Output: Training Texas Forest Service on NIST WUI 1 and 2 data collection methodology
Outcome: Adoption of the NIST WUI data collection methodology:
- USFS Region 8 (Southern US) is in the process of adopting. Other regions will be targeted in the future.
- National State Foresters Association – Proposal for adoption of WUI data collection methodology (by invitation, in June 2011).
- Texas Forest Service use of data collection methodology in Amarillo and other locations during 2011. NIST trained and then deployed with Texas to the Amarillo WUI fire.
- National Wildfire Coordinating Group – Active participation and proposal for adoption of WUI data collection methodology in National fire response framework (by invitation).
- NFPA and ICC Codes and standards – the NIST WUI data collection methodology has been proposed for inclusion in standards by both organizations.
A significant number of partnerships in addition to those described above have been developed which support project objectives^[3]

Standards and Codes: The standards strategy has three primary components:

Adoption of the developed WUI two-phase data collection methodology. This is done through several key organizations. The intent is for states and federal agencies (USFS, DOI) to collect reliable and consistent WUI structure ignition vulnerability data. NIST is working with NFPA and ICC.
Hazard reduction guidance – improvements to homeowner and builder best practices. NIST is working with NFPA to improve FIREWISE and other guidance documents. The structure ignition vulnerabilities identified in the project will be directly transferred to NFPA for inclusion in a Revised FIREWISE document.
Adoption of the WUI Exposure Scale under development. The WUI Exposure Scale will be used to guide building codes, standards and best practices in the WUI. Cost effective solutions will be enabled both for new construction as well as retrofit by building to meet specific WUI exposure requirements. Technical partnerships have been developed with key standard sand codes organizations (NFPA, ICC, ASTM) and key state agencies (CA, TX, FL) to enable this technology transfer.

^[1]. For example, at The Trails community in San Diego, CA, the Witch/Guejito fires in 2007 destroyed 74 homes and damaged 16. Out of the 74 destroyed homes 12 had wood shake roofs (of varying ages and treatments), while 37 had Spanish tile roofs (with and without bird stops), 24 had composite roofs and there was one metal roof. The wood shake roofs were present in 16% of the destroyed structures, while the Spanish tile roofs were present in 50% of structures. There were 245 structures within the fire line at the Trails. For the performance of roofs within the fireline 100% of wood shake roofs exposed were destroyed while only 24% of Spanish tile roofs were destroyed. By documenting all structures within the fire line, the relatively high (all other factors being equal) vulnerability of wood shake roofs stands out. While quantifying structure survivability is a complex process that involves construction particulars and measures of fire and ember exposure, the above example illustrates how misleading partial information can be.

^[2]. Joint Fire Science Program – Satisfactory review of WUI data collection methodology and Witch report.

IAFF support for Wildland and WUI fire activities including fire behavior characterization

^[3]. USFS FERA support for characterizing exposure and for WUI data collection

NFPA FIREWISE Program – A joint effort will result in a revised and improved Firewise checklist.

Partnerships with states agencies that have significant WUI problem areas: CA, FL and TX are close partners for technology transfer.

Joint Fire Science Program – dissemination of WUI methodology, structure ignition vulnerabilities and hazard mitigation solutions.

Committee on a National Cohesive Strategy as requested by US Congress (by invitation): active participation in Wildland and WUI data collection framework and Public Safety, Property Loss, & Social/Community vulnerability framework development.

North Texas Wildfires Spark Historic Federal-State Collaborative Study.

A member of a joint NIST-Texas Forest Service study team collects data on a Amarillo, Texas, building damaged by wildfires in February 2011. Photo credit: NIST.