The US Army’s 2nd Brigade, 1st Armored Division, Special Troops Battalion has been testing the Husky Mounted Detection System at White Sands Missile Range in New Mexico. The vehicle is equipped with ground penetrating radar capable of detecting buried improvised explosive devices, or IEDs, and anti-tank land mines. [Source: The United States Army. Image: US Army]
This allows accurate mapping of issue which have been under the ground just before any digging is done. If digging is accomplished very first, it is actually very likely to hit and break pipes and that may be particularly costly to replace, not to mention risky as what ever is in those pipes escapes into the surrounding spot.
Furthermore it is not restricted to detecting the presence of metals alone, it provides you an overall kaleidoscopic view of what is laying underground, which is what most of the engineers are concerned with, as the nature of projects varies they need their own GPR reports.