A Comparison of Remote Sensing Techniques for Centreline and Weld Mapping in Place of Manual Survey in Hazardous Environments

Many places where pipelines are built have soil, basal material and water table conditions which can create suboptimal environments for centerline as-builting and weld mapping. Furthermore, ditches containing multiple pipelines can make as-built and weld mapping particularly complex especially when the pipes are of varying sizes. The complexity of the laying in of multiple pipes may also result in the ditch being exposed longer than desired, enabling further deterioration of ditch conditions and even flooding. At times, circumstances can become so hazardous that manual survey of the pipeline centerline can only be completed while the pipe is outside of the ditch (requiring a transposition) and a variety of survey techniques must be used to capture the centreline locations. Surveying at a distance from the pipes can make verification to weld mapping and field inspection problematic. Recent advancements in remote sensing, particularly mobile LiDAR and imagery collection technology, have lowered collection and processing costs and expanded the applicability of the technology to complex collection environments and harsh conditions on pipeline construction rights-of-way. Additionally, there has been a marked improvement in overall data accuracy and precision from mobile mapping systems. Up until recently, these technologies have only been useful in static construction environments where periods of inactivity during construction afforded the time to set up and collect data in a safe and accurate manner. New remote sensing systems, designed for more rugged, fast-paced, and complex environments are expanding the use of mobile remote sensing to the pipeline construction right of way. These mobile mapping technologies have significant advantages over drone collected data particularly with respect to the logistics of the data collection. Recently, advanced mobile mapping technology was employed on various pipeline construction projects and the accuracy of LiDAR and imagery collection for centerline as-builting and weld mapping was assessed. Some of the project locations were in areas where the traditional manual collection of data could be deemed hazardous or unsafe. This paper evaluates the collection technique against the traditional methods used under hazardous or inaccessible conditions and discusses the benefits of mobile remote sensing for this scenario. The authors also provide an analysis of the remote sensing based as-built and weld mapping data against those acquired through the traditional technique during this trial. Opportunities for adoption of this method as well as improvements to its application are also discussed.