ForConstructionPros.com

The nature of ARRA projects favors the use of half-lane mills for working on state and federal highways. "It's not about horsepower alone," says Sharp. "It's about matching horsepower to productivity and quality end product."

"The trends that we are seeing are more toward the big equipment. The size of the projects being let are very big, so people are trying to figure out how to get a lot of work done quickly," notes Irvine. "We have had a good run on RX900s with 12-ft. 6-in. drums [for] full-lane milling. The half- and full-lane, 900-hp-type machines are definitely in demand."

Jim Holland, Terex Roadbuilding, acknowledges, "There seems to be an increase going toward the full-lane mill. It will never overtake the half-lane, mid-range by any means." However, the full-lane mills can be used at night, an overlay can be applied and the road can be opened up to traffic the next day.

The ARRA is only one driver in the popularity of large milling machines. Another is the desire for states to stretch their budgets. "They are doing this through fractionating RAP and increasing recycle percentages," says Irvine. For instance, North Carolina is experimenting at 40% RAP; South Carolina varies from 30% to 50%; Wisconsin is increasing to 25%; Florida is going to 45%; and Kansas is going to 30% to 40%. "These were typically 10% to 15% RAP states."

According to Irvine, at 10% to 15% RAP, you typically have one large RAP pile. When you load a bucket out of this pile, you really don't know what you might get. It could be just a bucket of fines; fines contain only 7% to 9% asphalt.