Some Experience with Geospatial Imagery and Route Optimization

Abstract

The means by which three technologies, geospatial imaging, soft-copy photogrammetry, and alignment optimization, can assist in generating and evaluating plans for new road alignments are assessed. The technologies are illustrated by two case studies. One, based on satellite data, was selected as a case study of the technologies because planning had been in progress for several years and all the data except the satellite images were available. The study was conducted at a broad level to demonstrate the ability of the technologies to produce high-quality results quickly and to prepare material for presentation. Constraints were kept simple because the aim was to demonstrate the technology, not to undertake a detailed study of the options; and the road authority’s costs for earthwork and other construction were used to provide comparability with the ongoing study. The costs of the alignments produced by the optimization were about 25 percent less than those from the ongoing study, and there was a consensus that the combination of technologies could have cut 12 to 18 months off the planning process. The second study, based on aerial photography, was a straight application of the technologies with no comparison with other studies and had to provide all the detail required for public presentations. It was a full-scale planning study in which aerial photography and alignment optimization technologies were used to identify the best transport corridors, to generate a set of low-cost alignment options within the corridors, and to assess the various alignment options.