Heavy vehicles are defined as any vehicle having a weight (pounds) to horsepower
ratio of 200 or greater (Ref. 1). Crawl speed is defined as the maximum sustained
speed heavy vehicles can maintain on an extended upgrade. See Ref. 1 for graphs
showing the effect of grades on acceleration and deceleration of heavy vehicles.
Locale describes the character and extent of development in the vicinity. It can be
considered commercial, industrial, or residential, as well as rural or urban.