Without milling, what problem may occur when applying thin lift?

• A. Grade issues
• B. Improved traffic noise
• C. Faster construction
• D. Lower cost

Answer: (A)

Thin lifts depend on a smooth, correctly graded base to meet design elevations and slopes. Milling removes surface irregularities and restores proper grade and cross-slope, ensuring the new layer can be placed to the intended profile and bond well. If milling is skipped, the existing bumps, ruts, and highs are carried into the overlay, making elevations inconsistent and the drainage path off. This leads to grade issues where the surface doesn’t align with the planned grade, causing poor ride quality and potential premature distress. These problems aren’t about improving noise, speeding construction, or lowering costs; in fact, skipping milling often increases risk of failure and maintenance needs.