Wirtgen Group has introduced a new, intuitive machine control system specifically for its cold milling machines, designed to simplify the complex task of depth control. In traditional milling, operators rely on mechanical ski sensors or string lines to maintain the correct cutting depth. However, these methods are prone to errors, especially when transitioning between old pavement and new patches. Wirtgen Navigation replaces these mechanical references with a high-precision 3D guidance system.
The system utilizes a ruggedized tablet mounted in the cab, connected to GNSS receivers and total stations placed around the site. The tablet displays a color-coded map of the road surface, showing the operator exactly where to cut and how deep to go. More importantly, the system automates the milling drum's leveling. As the machine advances, the system sends signals to the drum's hydraulic leveling cylinders, automatically adjusting the depth by millimeters to match the design profile.
The key engineering feature is the "Millimeter Accuracy Slope Control." When milling a superelevated curve (banked turn) on a highway, traditional ski sensors can drift. Wirtgen Navigation uses a laser reference to maintain a strict cross-slope tolerance of +/- 0.05%. This precision ensures that the new asphalt layer is perfectly uniform, eliminating the "bird baths" (low spots) where water collects. During a recent airport runway renovation, the system allowed the contractor to mill off the top layer of asphalt with such precision that the new surface required 15% less material to lay, generating significant cost savings on the bitumen budget.
