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"Model Terrain" -- The Discovery Files

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A team of geographers has developed a series of models -- using a massive, crowdsourced, fitness-tracking database -- that strongly predict how terrain slope affects human travel rates. The geographers will apply their new models to wildland firefighters: During their spring training in 2019, nearly a dozen fire crews in Utah, Idaho, Colorado and California will use GPS trackers to record their movements and log their travel rates.

Credit: NSF/Karson Productions

Audio Transcript:

Hitting the slopes.

I'm Bob Karson with the Discovery Files, from the National Science Foundation.

If you've ever hiked hilly areas, you know that as the slope angle increases, travel gets harder and slower. When there are changes, we just adjust. But some occupations, such as wildfire fighter or wilderness rescuer may need to predict the time needed to move across the terrain in question. It could be a matter of life and death.

Researchers at the University of Utah saw the need for better mathematical models to help these responders. Currently, the most widely used way to estimate how slope affects travel rates is "Tobler's Hiking Function," designed using data collected in the '50s, before there was GPS. The next most widely used model sprung from hiking observations of a Scottish mountaineer in 1892.

The research team turned to crowd-sourced data from a fitness app and analyzed anonymous GPS info from the devices of 30,000 hikers', runners' and joggers. One result: a slow walk on a flat, one-mile trail averages about 33 minutes. The same level of exertion on a steep, 30-degree slope takes about 97.

Nearly a dozen fire crews in four western states will be using the new models during training, to help them gain more accuracy -- a little more predictability in some of the most unpredictable environments on Earth.

"The discovery files" covers projects funded by the government's National Science Foundation. Federally sponsored research -- brought to you, by you! Learn more at or on our podcast.

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