Research: selecting the optimum escape route at a wildland fire

Escape Route Index: A Spatially-Explicit Measure of Wildland Firefighter Egress Capacity

Escape Route Index

Above: a figure from the research

Previously we covered research that is underway to help wildland firefighters determine the best escape routes from a dangerous fire. A paper published in 2017 looked at the use of LiDAR to analyze the effects of slope, vegetation density, and ground surface roughness on travel rates for wildland firefighters’ escape routes. And earlier this year we reported on research that studied crowd-sourced fitness data to estimate rates of foot travel on slopes and how it could be integrated into recommendations for escape routes.

Below are excerpts from a research paper that was published July 8, 2019, written by Michael J. Campbell, Wesley G. Page, Philip E. Dennison, and Bret W. Butler. It is titled, Escape Route Index: A Spatially-Explicit Measure of Wildland Firefighter Egress Capacity. Link to the entire document.

From the Abstract

A previously published, crowd-sourced relationship between slope and travel rate was used to account for terrain, while vegetation was accounted for by using land cover to adjust travel rates based on factors from the Wildland Fire Decision Support System (WFDSS). Land cover was found to have a stronger impact on ERI values than slope. We also modeled Escape Route Index (ERI) values for several recent wildland firefighter entrapments to assess the degree to which landscape conditions may have contributed to these events, finding that ERI values were generally low from the crews’ evacuation starting points.

From the Conclusions

In this paper, we have introduced a new metric for assessing and mapping egress capacity, or the degree to which one can evacuate from a given location, on a broad, spatial scale based on existing landscape conditions. ERI is not a single metric, but a suite of four spatially-explicit metrics that define the relative travel impedance caused by terrain and land cover faced by a fire crew, should that fire crew need to evacuate. The intent is that this modeling technique will be employed to aid in wildland firefighter safety operations prior to engaging a fire, acting as a decision support tool. Given that the metric relies on US nationwide, publicly-available datasets, the goal is that ERI metrics would be mapped in advance of fire suppression and used to direct fire crews toward potential control locations with higher capacity for evacuation, thus reducing the potential for injurious or even fatal entrapments.

ERI does not map escape routes, per se, it highlights areas that have a greater or lesser capacity for providing efficient escape routes. Areas with high ERI values will likely have an abundance of open, easily-traversable terrain, through which many potential escape routes may exist requiring little alteration of the land cover. Conversely, areas with low ERI values possess some combination of rugged terrain and dense vegetation, thus making the designation of suitable escape routes difficult or even impossible.

Fitness tracking data from about 30,000 people used to determine travel rates on slopes

Researchers hope to use the information to help wildland firefighters find the best escape routes

Firefighters Whitetail Fire Black Hills
Firefighters on the Whitetail Fire in the Black Hills of South Dakota, March 8, 2017. Photo by Bill Gabbert.

Fitness tracking data from 29,928 individuals representing 421,247 individual hikes, jogs, and runs on trails in and around Salt Lake City was used to calculate travel rates on slopes. Researchers hope their findings can be used to help develop a smart phone app that would suggest to wildland firefighters the best escape route if faced with a possible entrapment.

Funding provided by the U.S. Forest Service and the National Science Foundation, helped Michael J. Campbell (Fort Lewis College), Philip E. Dennison (Univ. of Utah), Bret W. Butler (USFS), and Wesley G. Page (USFS) complete the research which is summarized in their paper, “Using crowdsourced fitness tracker data to model the relationship between slope and travel rates.”

They undertook the study basically because it had not been done before using a large amount of raw foot travel data and the information is needed to develop an app that can enhance the situational awareness of firefighters. Some preliminary work was done two years ago by some of the same researchers. They used Light Detection and Ranging (LiDAR) technology to analyze the terrain slope, ground surface roughness and vegetation density of a fire-prone region in central Utah, and assessed how each landscape condition impeded a person’s ability to travel. At the time, Department of Geography professor and co-author of that study, Philip Dennison, said, “Finding the fastest way to get to a safety zone can be made a lot more difficult by factors like steep terrain, dense brush, and poor visibility due to smoke. This new technology is one of the ways we can provide an extra margin of safety for firefighters.”

The researchers felt they needed more accurate travel rate data to build on their previous work to calculate the best escape routes.

The data used in this study were obtained from Strava, a popular fitness tracking and social networking app that allows users to track their movement while hiking, running, and cycling using GPS on phones or fitness tracking devices to compare their travel rates to their peers. The company aggregates and anonymizes the data and makes them available to planning organizations and researchers. The information used in the study represents hiking, jogging, or running a combined 81,000 miles.

“This will revolutionize our understanding with how terrain affects pedestrian movement,” said Michael Campbell, assistant professor at Fort Lewis College and lead author of the study. “From a firefighter perspective, under normal conditions a fire crew may have ample time to hike to a safety zone, but if the sh*t hits the fan, they’re going to have to sprint to get there. We tried to introduce predictive flexibility that can mimic the range of conditions that one might need to consider when estimating travel rates and times.”

“Calculating how quickly people move through the environment is a problem more than a century old. Having data from such a large number of people moving at all different speeds allowed us to create much more advanced models than what’s been done before,” said Phil Dennison. “Any application that estimates how fast people walk, jog, or run from point A to point B can benefit from this work.”

firefighter travel times slope
From the study. Click to enlarge.

According to the results of the study, a slow walk on a flat, 1-mile (1.6 km) trail takes about 33 minutes on average, whereas that same level of exertion on a steep, 30 degree slope will take about 97 minutes. On the other end of the spectrum, a fast run on a flat, 1-mile trail takes about six minutes, as compared to 13 minutes up a 30 degree slope. People move most rapidly on a slightly downhill slope, and travel rates were faster for downhill than uphill movement. For example, walking down a steep slope of 30 degrees was done at the same speed as walking up a slope of 16 degrees.

“For wildland firefighters, the slope of the terrain is largely what determines the most efficient path to safety, and dictates how long it’s going to take,” Mr. Campbell told Runner’s World. “Our goal is to provide firefighters with the ability to press a button on their phone and not only map the best route to safety, but also provide a travel time estimate.”

Of course hiking times on established trails is not always completely transferable to the situations faced by wildland firefighters. Presumably ground surface roughness and vegetation density from the earlier work will be factored in when developing the app to make the results more realistic.

Starting this month, the geographers will apply their new models to wildland firefighters. During their spring training, nearly a dozen fire crews in Utah, Idaho, Colorado and California will use GPS trackers to record their movements and log their travel rates. This will allow them to better understand the travel rates of the unique firefighter population, who are often traversing rugged terrain, working long hours, and carrying heavy packs.

Can technology determine the best escape route for firefighters?

Of the 22 research proposals funded by the Joint Fire Science Program in June, 16 of them were various ways of studying vegetation. At the time we wrote, “It would be refreshing to see some funds put toward projects that would enhance the science, safety, and effectiveness of firefighting.”

A recently completed study is directed toward the firefighters on the ground. The U.S. Forest Service has paid to have researchers study the feasibility of using LiDAR and computers to determine the most efficient and quickest escape routes if firefighters have to withdraw while attacking a wildfire. The LiDAR helped researchers evaluate how landscape conditions, such as slope, vegetation density, and ground surface roughness affect travel rates.

I have a feeling that there will have to be significant advances in portable handheld technology before fire crews in remote areas can take advantage of this type of data. However, who knows, maybe in 10, 20, 30, or 40 years grunts on the ground will have access to sophisticated tools that we can’t even imagine today. They might just speak into a lapel pin to ask for the best escape route, and an augmented reality head-up display or an orbiting drone with a visible laser will designate the path.

Even though the research was paid for by United States taxpayers through the U.S. Forest Service, those same taxpayers will be charged a second time if they want to see the full results of their investment. The fee is $25 to get a copy of the .pdf. It may be available months or years down the road at no additional cost.

The title of the paper is, A LiDAR-based analysis of the effects of slope, vegetation density, and ground surface roughness on travel rates for wildland firefighter escape route mapping.

A year ago the same group of researchers studied how to find and evaluate safety zones in a paper titled, Safe separation distance score: a new metric for evaluating wildland firefighter safety zones using lidar. This research IS accessible to taxpayers without paying a second time.

The recent paper about escape routes was written by Michael J. Campbell, Philip E. Dennison, and Bret W. Butler. Here is a summary of some of their findings.


Every year, tens of thousands of wildland firefighters risk their lives to save timber, forests and property from destruction. Before battling the flames, they identify areas to where they can retreat, and designate the best escape routes to get from the fire line to these safety zones. Currently, firefighters make these decisions on the ground, using expert knowledge of fire behavior and assessing their ability to traverse a landscape.

Now, a University of Utah-led study has developed a mapping tool that could one day help fire crews make crucial safety decisions with an eagle’s eye view.

The new study is the first attempt to map escape routes for wildland firefighters from an aerial perspective. The researchers used Light Detection and Ranging (LiDAR) technology to analyze the terrain slope, ground surface roughness and vegetation density of a fire-prone region in central Utah, and assessed how each landscape condition impeded a person’s ability to travel.

Escape Route wildfire“Firefighters have a great sense for interactions between fire and landscape conditions. We hope to offer to them an extra tool using information collected on a broad scale,” says lead author Michael Campbell, doctoral candidate in the U’s Department of Geography.

Department of Geography professor and co-author, Philip Dennison, adds, “Finding the fastest way to get to a safety zone can be made a lot more difficult by factors like steep terrain, dense brush, and poor visibility due to smoke. This new technology is one of the ways we can provide an extra margin of safety for firefighters.” Continue reading “Can technology determine the best escape route for firefighters?”