The Size Factor
Jason Averill of the National Institute of Standards and Technology talks about the landmark study linking firefighter crew size with fireground performance

NFPA Journal, July/August 2010

Does crew size really matter? That’s the question Jason Averill of the National Institute of Standards and Technology (NIST) and other researchers answered in the recently released "Report on Residential Fireground Field Experiments." Noting minimal research on firefighter response times and the impact of varying crew sizes (though the International Association of Fire Fighters and local jurisdictions have published somewhat similar studies in the past), the report provides data on the relationship between crew size and firefighting activities involving single-family home fires, which are responsible for the largest share of firefighter (as well as civilian) deaths and injuries.

For the study, the Montgomery County Fire Department in Maryland and the Fairfax County Fire Department in Virginia completed 60 controlled fire experiments last year at the Montgomery County Public Safety Training Academy in Rockville, Maryland. Analyzing 22 firefighting and rescue tasks — including occupant search, laddering, and ventilation — researchers discovered key variations when comparing firefighter crew sizes. A four-person crew, for example, completed all fireground tasks at a low-hazard residential fire — that is, a fire involving a 2,000-square-foot (186-square-meter) single-family home with no special hazards — 30 percent faster than the two-person crew, while a four-person crew completed the tasks 25 percent faster than a three-person crew. Comparing the performance of three- and two-person crews, total task completion time improved by 8 percent.

Averill, one of the study’s principal investigators, is group leader for NIST’s Engineered Fire Safety Group, which translates results of its studies into tools for a range of stakeholders. He recently spoke with NFPA Journal about the study’s highlights and its potential impact on the fire service. To view a pdf of the full report, visit www.nist.gov/customcf/get_pdf.cfm?pub_id=904607.  

Why is there a need for this study? Wouldn’t common sense tell you that a four-person crew is more effective than a two-person crew?
In 2001, NFPA 1710, Organization and Deployment of Fire Suppression Operations, Emergency Medical Operations, and Special Operations to the Public by Career Fire Departments, was passed. It became reasonably clear during deliberations of that standard that additional scientific data would be helpful to quantify the effects of arrival times and crew size and basic deployment variables on the results of fire service performance. Shortly thereafter, NIST, the International Association of Fire Fighters, the International Association of Fire Chiefs, Worcester Polytechnic Institute, and the Commission on Fire Accreditation International decided to collaborate on research that would provide that basic understanding. The Urban Institute conducted the statistical design for a survey of 400 career and combination U.S. fire departments.

One hundred years of fire service experience has told people that there are performance differences as a function of crew size—the difficulty for public policy makers, city and county managers, fire chiefs, and anybody who’s tried to deal with this issue is that they don’t know how much difference it makes. One of the primary goals of this project is to provide a technical foundation for NFPA 1710. The results of this study will help quantify the magnitude of the risks faced by firefighters responding to the most common structure fire.

How can the fire service best utilize the report? 
At the beginning of the Congressional Fire Services Institute meeting in April, Jeff Johnson, president of the International Association of Fire Chiefs, issued a challenge to his membership: "I challenge every fire chief in this country to read and understand this report." I think this statement is key. If the fire service reads and understands this report, it gives important insights into what’s going on at the fireground and the dynamics for their particular situation. Each locality needs to look at this report and decide what it means in the context of the resources they have available, and match that with the risks they face in their community. That’s one of the things we keep coming back to in this study—it provides people with the ability to match resources to risks. The objective of this is not to come up with a one-size-fits-all solution, but to allow each local community to come up with a solution that works for them.

How do you plan to get the word out about the report?
We received a grant from the Federal Emergency Management Agency’s Assistance to Firefighters Grant Program, and one of the deliverables is to take this report and put it into teaching and learning materials that the fire service can utilize in order to help it interpret and digest the details. These materials are going to be available late this summer or early fall. It will include a PowerPoint, videos, an executive summary of primary findings, and a guide to interpreting and understanding what’s in the report. It’s also appreciating not only what the report does say, but also what it doesn’t say, so everyone understands the limitations. For example, this data doesn’t apply to a response to a high-rise building. We didn’t look at the effects of sending more or fewer apparatus to the fireground. We had four apparatus; we didn’t look at sending six, seven, or eight. We want to be very clear about what’s in, and what’s not in, the report. In the long term, one of the goals of the project is to provide quantitative tools that assist local decision makers with quantifying the effects of changes in their deployment configurations. 

Why does this study focus only on fires at single-family residences? 
NFPA statistics clearly demonstrate that the residential fireground is where most civilian injuries and deaths occur. It’s one of the most common responses of the fire department, and it establishes a baseline. This is one of the least hazardous responses the fire service deals with, and yet, because of its frequency, continues to bring about firefighter injuries and firefighter deaths. Not only are we developing an understanding related to firefighter and civilian injuries and deaths, but this establishes a floor, because there are many more responses that fire departments deal with that are more hazardous than this.

What are the study’s key findings?
Something that’s certainly generated some discussion is the overall lack of differentiation of five- and four-person crews. [The report indicates that adding a fifth person to crews responding to fires at single-family residences did not reduce overall fireground task times.] There are a few important tasks where the five-person crews did make a difference. The first was a performance gain—six percent faster—for the time to put water on the fire for a five-person crew over a four-person crew. Second, the time for laddering the structure was improved by an average of 13 percent. However, in general, the performance times for five-person and four-person crews were relatively similar. That would seem to be consistent with a low-hazard residential structure fire. We’ve noted, and other studies have found, that in high-hazard responses [such as fires involving high-rise occupancies and industrial facilities], five-person crews are beneficial when the risks are escalated. Also, the findings indicate that three-, four-, and five-person crews all had similar rescue times, and all three crew sizes had faster rescue times than two-person crews. Comparing the performance of three- and two-person crews, total task completion time improved by nearly 8 percent, and this completion time improved by 25 percent when comparing three- and four-person crews.

What are your thoughts on these conclusions?
Fire departments now have a quantifiable understanding of the performance level of the two-person crews relative to what you get with other sized crews for this class of structure fire. Now, the decision makers have that quantifiable understanding of the increased risk posed to firefighters and to the general public in terms of life safety. 

Who supplied the funding for the study?
It took a long time to find the right funding sources. This project was one of the first research-section grants in the Assistance to Firefighter Grants Program. That initial grant laid out the overall structure, and it’s reflected in the study’s title. We did extensive literature review and put together a theoretical model to understand the important variables.

Were EMS times calculated for this study?
They were not reported in this report, but we did collect data on EMS performance, particularly in the context of understanding not just crew size, but where Advanced Life Support providers are stationed and deployed. Those results are still being analyzed and are not part of this report, but we hope to have that data available shortly.    

Why was it important for this project to be a collaborative effort?
We needed the unique expertise that each organization could bring to the table. [NFPA Regional Manager] Russ Sanders is a technical expert who has been involved with the project since inception. His in-depth knowledge of firefighting tactics and operations through his experience as a chief of a major city and his insight into the application of our work to codes and standards has been invaluable to the design, execution, and analysis of the research. We needed the ability to bring in groups like Montgomery County and Fairfax County firefighters. We needed the public policy perspectives of the fire chiefs. We needed the technical expertise that some of our experts were able to bring. NIST provided the capability to do field tests over a period of weeks. The Urban Institute brought its rigorous statistical analysis of data from the fireground experiments. Worcester Polytechnic Institute brought public policy perspectives. This approach ensured us that no particular agenda was being brought forward. This was a truly collaborative process.

— Interview conducted by staff writer Fred Durso, Jr.