The Use of Lidar to Facilitate Design and Construction of Pipelines

Within the last decade, airborne lidar (Light Detection And Ranging) equipment has evolved to the point where it can provide accurate ground surface elevations on a dense grid (often 1m by 1m) along pipeline corridors, at a cost that is a fraction of the cost for a comparable ground based topographic survey. This paper explains how lidar is used to acquire topographic data and how the data are converted to digital terrain models referenced to geodetic benchmarks. The accuracy and density of topographic data acquired by lidar surveys can be used to greatly facilitate pipeline design and reduce pipeline construction costs. The major benefits include: 1) The density of ground surface elevations obtained using lidar are significantly better than can be obtained using photogrammetry or conventional ground based survey methods. 2) The survey data can be collected over large areas in a matter of days and with virtually no disturbance to landowners. 3) The digital terrain models derived from lidar survey data can be imported into existing drafting (CAD) software and used to efficiently generate centerline profiles, cross-sections and alignment sheets as required for pipeline design and construction. 4) Hillshade maps derived from lidar data have proven extremely useful in pipeline route studies because they allow surface features to be identified and often avoided, thereby minimizing pipeline construction and operating costs.