For wildland firefighters retreating from the fire to a safety zone, predicting how long it takes to move across terrain can be a matter of life and death. Geographers developed a series of models that strongly predict how terrain slope impacts travel rates. Using a crowdsourced fitness-tracking database, they analyzed GPS data from nearly 30,000 people. The resulting models are the first to account for variability in travel rates between slow, medium and fast movers.
