An asphalt plant will produce 180 tph for a highway project. The mat will be 12 ft wide and 1!-in. thick, and will have a density of 115 lb/sy-in. A vibratory roller with a 66-in.-wide drum will be used for compaction. Assume a 50-min hour efficiency factor for the roller.
The overlap between adjacent laps and over edges will be 6-in. minimum. It is estimated that nonproductive travel will add about 15% to total travel.
From a test mat, it was found that three passes with the roller are required to achieve density. To account for acceleration and deceleration when changing directions, add 10% to the average roller speed to calculate a running speed. If it is desired to keep the rolling speed under 3 mph, how many rollers are required for the project?