For almost any construction project it is necessary to investigate ground conditions and to find and locate precisely the presence of any existing buried utilities or structures. This can be a major challenge for utility work in crowded public rights-of-way. In this category are the methods that can assist in determining the presence and location of buried objects without extensive excavation from the ground surface. Some approaches can provide the precise 3-D location directly. Other methods may have less precision but identify the approximate location and depth of the objects and allow further investigation, such as potholing, to confirm precise location and the detailed characteristics of the object. The procedures and technique used in a systematic engineering approach to utility asset location are referred to as “subsurface utility engineering”. In this approach, asset location information is certified by a registered/certified professional engineer and the level of knowledge and precision about utility location is categorized using defined levels of certainty/uncertainty.