Standardizing nondestructive underground utility survey methods

Are underground utility (UU) surveys specialist work? The answer was likely 'yes' when UU survey technologies were uncommon. However, the answer is increasingly 'no', as UU surveying has become a standard procedure to implement before digging. This is due to engineers and surveyors having gradually accepted the following two facts. On one hand, there is a high risk that an open trench lacking a proper UU survey will lead to accidents and associated costs. On the other hand, non-destructive/geophysical UU surveys produce less accurate results than land survey methods that are based on line-of-sight observations. Given these two facts, the transition from specialised to regular UU surveys requires the standardisation and harmonisation of the expectations among clients, consultants, contractors and service providers, particularly as survey findings in most civil engineering contexts reflect interpretations made by a survey team rather than definitive answers. Therefore, this paper standardises the workflows of three common UU survey technologies to devise a holistic five-tier survey plan. It also examines the accuracies and limitations of these technologies to develop five classes of survey quality applicable to any given UU. These survey technologies are pipe cable/electromagnetic locating, groundpenetrating radar, and light detection and ranging. Standardisation thus paves the way for the accreditation of professional UU service providers based on the components of man, machine, material, methods and environment (4M1E) under the framework in ISO/IEC 17025 by worldwide accreditation body.