Locational accuracy of underground utility mapping using ground penetrating radar

Many of today’s underground utilities are reaching the end of their practical life and need to be replaced or repaired. At the same time, new utility installations due to urban expansion and development of new communication technologies such as broadband are in progress. Hence accurate information of these utilities is essential for utility owners, engineers, contractors or surveyors, particularly as reference for excavation. Ground penetrating radar has been widely used in extracting information of buried utilities for better utility maintenance and management. The widely used scanning technique (i.e. ‘perpendicular-to-pipe’ scanning) is limited for retrieving the precise position of targets due to the effects of surrounding media. This paper provides a solution for the prevention of failed excavations by means of precise underground utility mapping. This paper first of all examines the accuracy of the commonly used data acquisition scanning technique, by conduction a series of tests, and then developed a better method. Subsequently, a real-life experiment was carried out to validate the performance of the proposed new scanning technique, to demonstrate its accuracy and effectiveness. We found that our method was able to do ‘along-pipe’ scanning with very high precision (i.e. less than +0.10 m, conforming to Quality Level A utility data). Hence, the proposed method set as a new benchmark for using ground penetrating radar for precisely locating buried utilities.

► Locational accuracy of underground utility mapping is crucial for the prevention of “blind” excavation.
► The GPR data acquisition approach is the key parameter to determine locational accuracy of underground utility mapping.
► ‘Along pipe’ scanning technique is capable of achieving accuracy of Class A utility (better than ±10 cm).
► Retrieval of GPR Class A locational accuracy provides opportunity for subsurface 3-D cadastral systems in the near future.