Geographic Information Systems/National Elevation Data Route Mileage Verification

Abstract

Maintaining the nation’s roads and highways is a critical national infrastructure activity. To do so requires that accurate inventories of roadway features as well as the roadway network itself be maintained. This paper addresses the accuracy of road network mileages, that is, the lengths of various road segments and routes. A study was conducted using Geographic Information Systems to determine the accuracy of using national elevation data (NED) to calculate these lengths. The advantage of doing so is that, if successful, costly and time consuming field studies could be eliminated or reduced. This savings could positively impact all State Departments of Transportation. The scope of the study includes interstate roads as well as all other road types including secondary roads. The primary contribution of the paper is its finding that using NED data provides significant advantages over field studies and provides a very acceptable accuracy level. It also identifies areas of questionable accuracy and indicates why. Additionally, the paper provides some insight into secondary road data which is an often neglected area.