Which of the following scenarios would most likely require the use of a pneumatic tire roller for the primary compaction phase, rather than a smooth drum vibratory roller?

Question: Which of the following scenarios would most likely require the use of a pneumatic tire roller for the primary compaction phase, rather than a smooth drum vibratory roller?

Answer options:

• A 300 mm lift of coarse gravel roadway base ✅ A 75 mm overlay of hot mix asphalt on a residential street
• A 250 mm lift of clay-rich subgrade requiring breakdown of clods
• A 150 mm layer of sand cushion for utility pipeline bedding

Correct answer: A 75 mm overlay of hot mix asphalt on a residential street

Explanation: Pneumatic tire rollers are excellent for the primary compaction of hot mix asphalt overlays due to their kneading action that densifies, seals, and reduces segregation in the asphalt without fracturing aggregates.