“Long year” feels positive
Here is a lineup of equipment used for paving the two-lift surface course on this project: A Roadtec SB-2500 material transfer vehicle leads, followed by a new Blaw-Knox PF-5510 paver. For the inside lane and shoulder pass, the paver is set up to make a nominal 16-ft-wide strip, followed by the outer lane and outer shoulder passes, both that are nominally 12 ft wide. Each seam between the lanes is overlapped by 6 in. so the two surface course lifts’ seams do not correspond. For example, if the inside lane lift is 16 ft 3 in. wide, the second (top) lift is 15 ft 9 in.

The paving train continues on with the three new BOMAG rollers in line. It starts with the BW190AD-4 AM tandem vibratory roller used in the breakdown position. Its operating weight is 26,896 lb. The working width is 79 in. with the front drum featuring the Variomatic system. Douglas said it requires only three passes with this roller in the vibratory mode to bring the material to specified density.

The intermediate roller is a BOMAG BW11RH static pneumatic tired roller. Its operating weight, including water ballast, is 27,000 lb. It features nine (five on the front axle, four on the rear axle) overlapping pneumatic tires, which brings the working compaction width to 68 in. Two compaction passes are made when the asphalt material is about 190°F.

Bringing up the rear as the finish roller is a BOMAG BW278 tandem vibratory roller. This roller has an operating weight of 20,600 lb and a working width of 78 in. It commences rolling once the asphalt material has reached 150°F. Two passes are required with the drums set in the static mode.

In order to ensure exceptional ride smoothness, Barilla measures the first surface course lift rather than wait for measuring only the final lift. Measuring for smoothness is accomplished by using a straight-edge measuring device. “For achieving the optimum riding characteristics on the roadway, I evaluate the surface smoothness results starting with the first 50-mm lift. If there are any corrections to be made to this lift, they can be made immediately. If we wait and make the paving corrections after the final [second] lift is put down, it will compound our correction problems. It is both very time consuming and more costly,” said Barilla.

Unlike some smooth ride test systems that are either installed on or pulled by a motor vehicle, Barilla uses a Hearn walk along straight edge. Riding on large-diameter bicycle-like wheels, the straight edge can easily be either pushed or pulled by one person. Barilla has no problem staying up with the paving train. The measurement results are automatically recorded on a roll of graph paper. Any dramatic road smoothness deviations recorded can be corrected straight away. Barilla said that smooth paving results using the present paving train have been outstanding, and with the second lift in place will result in receiving bonuses from NCDOT.

So far, both Moyers and Joe Bailey, NCDOT resident engineer, are very satisfied with the results of the paving. “It is 2007 that will be the ‘long year’ for paving on this project, but I am confident we will continue to achieve very good results. We have put down enough paving in 2006 with quality results that I see no reason why it will not continue,” said Moyers.

Bailey agreed with Moyers and sums it up as follows, “This project is going well, which includes the paving results, and a major reason is we [NCDOT] have two outstanding contractors [Goodson and Rea]. Both companies have a good reputation for doing quality work.”

Garrett is a freelance writer based in Bernville, Pa.
All of the asphalt paving for this project is Superpave, with the Rea Contracting part of the project totaling 500,000 tons of hot-mix asphalt. This HMA quantity includes what is needed to pave the four shoulders, which consists of two 50-mm lifts. © copyrighted Scranton Gillette Communications, Inc.