Purpose of the paper: Unintended damage to subsurface utilities during excavation is a major cause of disruption in electricity supply, telecommunication, water supply and other essential public services. Utility strikes are also a leading cause of hazardous liquid and natural gas accidents. Globally, services being struck cost billions of dollars each year. The purpose of this paper is to provide an overview of available non-destructive technologies (NDT’s) for subsurface utility detection.

Methodology: The background, limitations and advantages of available NDT’s were investigated. In typical NDT’s, energy is transmitted into the ground and the reflected energy from subsurface utilities is recorded. Processing of the recorded information produces data about the distribution of physical properties associated with the underground objects. Leading NDT’s for utility detection includes: Ground Penetrating Radar (GPR), Electromagnetic (EM) Methods, Low-Frequency Electromagnetic Fields, Magnetic Methods, Acoustic Emission Methods and Infrared Thermography.

Findings: Available NDT’s can locate underground services and can therefore diminish unintended utility strikes. However, these technologies can be unreliable, and the accuracy of the applicable NDT should be determined, while considering the relevant site circumstances. GPR is considered the most sophisticated NDT for utility detection. Applying GPR and EM methods in combination is the most effective solution for most underground survey conditions.

Value of paper: Locational data for underground services is often unavailable or inaccurate. Existing utilities are frequently damaged during construction excavations, causing project delays and unplanned expenses for all parties involved. The use of NDT’s can reduce the risk of damage caused to existing services and avoid substantial costs and time delays. However, the limitations of these NDT’s should be borne in mind.