The predicted weather will slow the spread of the fire the rest of this week
8:45 a.m. PDT Sept. 13, 2022
Bolt Creek Fire Sept. 10, 2022. Image from Path Least Taken video
The two hikers who found themselves nearly entrapped by the rapidly spreading Bolt Creek Fire in northwest Washington near Skykomish have posted a video describing how they escaped.
After nearly reaching their goal of the top of Baring Mountain on Saturday September 10, they realized the smoke noticed earlier was from a fire that started that morning and had become a threat to their lives. The two of them shot video off and on during the entire hike, and on Sunday “Path Least Taken” posted an expertly-edited version on YouTube. He explained that he debated about publishing it, but did so “as an educational tool to point out all of the mistakes we made that ended up putting our lives in danger.”
During the escape they used wayfaring skills and technology tools to figure out how to descend the very steep slopes while avoiding the fire, which was at times exhibiting extreme flame lengths many times the heights of the trees, as you can see in the above image from their video.
When the Bolt Creek Fire was mapped Monday evening it had burned about 9,400 acres. In several places it has spread downhill nearly to US Highway 2. The fire activity was very much diminished Monday by much higher relative humidity. A weather station at Index northwest of the fire recorded very light winds Monday with the RH ranging from 57 to 92 percent, conditions not conducive to rapid fire spread.
Bolt Creek Fire 3-D map, looking NNW at 7:41 p.m. Sept. 12, 2022.
“It’s been a good day today for firefighters,” said Jim Cahill, a Washington State Department of Natural Resources spokesperson Monday evening.
As of Monday night US Highway 2 was closed from Milepost 32 to Milepost 50 and the community of Index was under a “Go Now” evacuation order.
The spot weather forecast for Tuesday predicts temperatures around 60 degrees, minimum RH of 87 percent, and light winds becoming 5 to 6 mph in the afternoon out of the northwest. Tuesday night the RH will rise to 100 percent and drop to only 86 percent on Wednesday. On Monday and Tuesday there is a 13 to 16 percent chance of very light rain, about 0.03″. The humidity is expected to remain mostly in the 80s and 90s through Sunday. The fire will not spread rapidly under these predicted conditions.
Bolt Creek Fire map. The red line was the perimeter at 7:41 p.m. Sept. 12, 2022. The white line was the perimeter about 48 hours previously.
Granite Mountain Hotshots hike to the Yarnell Hill Fire, the morning of June 30, 2013. Photo by Joy Collura.
When crews of wildland firefighters in a remote area have to quickly move to a safer location due to an approaching flaming front, they hike on what they call an escape route to get to a safety zone where they can be out of danger without having to deploy their fire shelters. An average of 11 firefighters die each year while fighting fire. Of these deaths, about 44 percent are caused by entrapment or burnover events.
A key to moving to a safety zone is the travel time. Underestimating the required time can be fatal, in the worst of circumstances. That may or may not have been one of the many factors involved in the deaths of 19 firefighters on the 2013 Yarnell Hill Fire in Arizona.
Firefighters know how long it takes them to hike the three miles within less than 45 minutes while carrying 45 pounds as required by the Pack Test, or Work Capacity Test. From that it’s pretty easy to calculate their miles per hour. But that is on flat ground, a situation that is not always the case when escaping from a wildfire. Throw in steep uphill or downhill slopes, and the times will increase.
Previous research on the subject includes:
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.
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.
A new study uses a different database for the speed at which fire crews can hike. It is titled, “Modeling Wildland Firefighter Travel Rates by Terrain Slope: Results from GPS-Tracking of Type 1 Crew Movement.” (download, 2.3 Mb)
As the name implies, instead of using public crowd-sourced hiking speed data, the researchers issued GPS units to nine Type 1 Interagency Hotshot Crews in the Spring of 2019. Nine of the 11 participating IHCs received seven GPS units each, and the other two received 20 GPS units each. In addition to the GPS units, crews were provided with data collection sheets and armbands to carry the GPS units.
Using data collected by firefighters — a uniquely physically fit population that usually carries heavy loads while moving — provides a set of robust, adjustable travel rate models built from instantaneous travel rate data that can be applied in a variety of contexts.
The data was collected while on training hikes. Rather than rely on GPS for elevation, which is not always accurate, only locations having the more accurate lidar data were used.
The tables below are from the research paper.
Demographics of the Type 1 crews.
Here is an excerpt from the paper:
“The effects of the slope on the instantaneous travel rate were assessed by three models generated using non-linear quantile regression, representing low (bottom third), moderate (middle third), and high (upper third) rates of travel, which were validated using k-fold cross-validation. The models peak at about -3o (downhill) slope, similar to previous slope-dependent travel rate functions. The moderate firefighter travel rate model mostly predicts faster movement than previous slope-dependent travel rate functions, suggesting that firefighters generally move faster than non-firefighting personnel while hiking. Steepness was also found to have a smaller effect on firefighter travel rates than previously predicted. The travel rate functions produced by this study provide guidelines for firefighter escape route travel rates and allow for more accurate and flexible wildland firefighting safety planning.”
The authors of the paper are, Patrick R. Sullivan, Michael J. Campbell, Philip E. Dennison, Simon C. Brewer, and Bret W. Butler.
Escape Route Index: A Spatially-Explicit Measure of Wildland Firefighter Egress Capacity
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.
Researchers hope to use the information to help wildland firefighters find the best escape routes
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.
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.”
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.
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.
“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?”
