Wirtgen Group has announced a major safety and operational upgrade to its line of large cold milling machines, integrating Ground-Penetrating Radar (GPR) directly into the chassis to prevent accidental strikes on buried utilities. In urban road rehabilitation, milling through unmarked fiber optic cables or high-pressure gas lines is a constant, highly dangerous risk. Traditional methods require crews to manually hand-dig test trenches ahead of the milling machine, a process that delays projects for days. Wirtgen's new system, dubbed MillProtect, scans the subsurface in real-time and automatically lifts the milling drum if a dense object is detected.
The system utilizes a tri-array of high-frequency GPR antennas mounted on the front of the machine, just ahead of the milling drum. As the cold planer advances, the antennas emit electromagnetic pulses into the asphalt and subbase. The system's edge-computing module analyzes the signal reflections, differentiating between the natural density variations of gravel subbase and the distinct, high-conductivity signatures of metallic pipes, plastic conduits, or direct-buried cables.
The engineering challenge was bridging the gap between detection and physical reaction. If a utility is buried just two inches below the desired milling depth, the machine has milliseconds to react. Wirtgen engineered a high-speed hydraulic lift circuit for the drum. If the GPR detects a threat entering the cutting path, the control module instantly commands a rapid-flow directional valve to dump the drum lift cylinder pressure, forcing the heavy cutting drum upward by two inches in less than half a second, completely bypassing the standard electronic pilot controls.
During a recent municipal road project, the MillProtect system successfully identified and avoided an undocumented 4-inch cast-iron water main that was shallower than the project's 6-inch milling depth. By automating the utility avoidance process, Wirtgen is allowing contractors to operate large cold planers at full production speeds in dense urban environments without the constant threat of catastrophic infrastructure damage.
