Velocity-Based Terrain Coefficients for Time-Based Models of Human Movement

• Main Authors: Michelle de Gruchy, Edward Caswell, James Edwards
• Format: Article
• Language: English
• Published: University of York 2017-05-01
• Series: Internet Archaeology
• Subjects: archaeology; GIS; Least Cost Paths; Terrain Coefficients; Time-based Route Modeling; Tobler's Hiking Function; Naismith's Rule
• Online Access: http://intarch.ac.uk/journal/issue45/4/index.html

Few studies have calculated the relative difficulty of walking across different types of terrain (e.g. grass, asphalt, loose sand, and so on). Nonetheless, these relative values, called terrain coefficients, are integral, alongside slope, for generating computer models of human movement, whether for emergency planning, development, archaeology, the impact of ecological change on migratory patterns or any other purposes. Additionally, the few studies conducted evaluate this relative difficulty through metabolic rate measured through oxygen consumption. We demonstrate that these values are only appropriate for energy-based models (e.g. easiest routes), because it is unlikely that the relationship between metabolic rate and velocity is linear even when terrain is held constant. Rather, our work (returning to four terrains from these earlier studies and adding three additional terrains) investigates the relative effect different terrains have on a person's walking speed, finding the effects to be smaller, with statistical significance occurring on an entirely different scale from previous studies. Therefore, these terrain coefficients should only be used for time-based models (e.g. fastest routes).