About the research
This report discusses the use of LIDAR-derived surface terrain information to locate (or determine the location of) new transportation facilities or relocate existing facilities. Terrain information is used to construct and evaluate alternative routes and to create final design plans that optimize alignments and grades for the selected alternative. Currently, ground surveying and photogrammetric mapping are the methods used by state departments of transportation to acquire these data. Both methods are time and resource intensive since they require significant data collection and reduction to provide the level of detail necessary for facility location. These methods are also limited by environmental factors such as weather. The use of light detection and ranging (LIDAR) to supplement the design process is presented in this report. Early research results as well as surveyed literature indicate the LIDAR data cannot replace photogrammetric data in the final design stages of the highway location and design process. Results also indicate that LIDAR accuracy is less consistent than indicated by vendors. The true potential of LIDAR in this process appears to be a supplemental form of data collection to photogrammetry. LIDAR could be collected for large area corridors, providing designers with the terrain information necessary to identify favorable alignments at earlier stages. Once such alignments have been identified, detailed photogrammetric data could then be produced for a lesser area. The result could be a significant savings in time and possibly money–through labor savings–using this modified data collection approach.