The impacts of grain subterminals on rural highways
The problems associated with increased heavy grain truck traffic in rural regions were investigated. Both the short-run incremental costs of accelerated pavement replacement and the long-run incremental costs of upgrading low-volume highways were considered. A set of demand and traffic models was formulated which projects the annual flow of grain from each production zone in an impact region to each elevator, allocates the flows among truck-types, computes the annual trips, gross vehicle weights and axle weights, and assigns the truck trips to the highway network. A set of highway models was also formulated which computes the equivalent single axle loads for each highway section in an impact region and estimates the incremental costs associated with subterminal traffic.
The impacts of a newly-formed subterminal-satellite elevator system in rural North Dakota were investigated. The results of the case study indicate that rural collector highways are likely to experience substantial localized impacts from subterminal development but the effects on principal arterials may be minimal. Altogether, $1.14 million in short-run costs and $8.41 million in long-run costs were projected for the impact region. However, the case study roads represent less than 2 percent of the rural arterial and collector highway mileage in the state. If the case-study network represents a microcosm of rural North Dakota, then the statewide short-run and long-run incremental costs may be in the vicinity of $57 million and $420 million respectively. However, regional variations within the state may result in either higher or lower costs for a given elevator system than those projected in the case study.