Conti said Lindy would usually pave the 10-foot shoulder first. That way, when paving the driving lane, the rollers could arc over onto the shoulder to change direction. In the same way, when pulling the passing lane and shoulder, the rollers could arc over onto the just-placed driving lane to stop and change direction.
Lindy used a Roadtec SB 2500 Shuttle Buggy to remix the asphalt on the job and transfer it from trucks to the paver. "The Shuttle Buggy is an absolute necessity," says Tutino. "It provides for continuous paving, it prevents trucks from bumping the paver, and it remixes the asphalt to prevent segregation. Plus it affords faster delivery to the paver."
Tutino said Lindy was one of the first, if not the first, contractor in Pennsylvania to use a material transfer vehicle in asphalt paving. "We had a Barber Greene remixer, then Roadtec came out with the Shuttle Buggy," Tutino recalls. "Back in the early 90s we were one of the first contractors to use a Shuttle Buggy, even though it cost us more. Then within two or three years, Pennsylvania began to effectively specify a Shuttle Buggy, because they write the spec for segregation in a way that leads you to use one."
Before each shift, Lindy held meetings of the crew to discuss safety, production rates, roller techniques, and the general layout of the work for the shift. The length of pavement per shift determined the speed of the paver, and then plant production matched paver speed.
Start times for the trucks were staggered to spread them out and still meet production goals. Production rates changed daily, but generally ran in the area of 250 to 350 tons per hour.
Conti said Lindy ran a profiler behind the paving crew to monitor the ride of the freshly compacted asphalt. "We maintained constant communications among three people - the ride technician who runs the profiler, the nuclear density gauge operator, and the paving foreman," says Conti. "That way if some sort of adjustment needed to be made, we could make it in a timely fashion.
"We monitor the profiler numbers, and we know what they should look like," says Conti. "So if the profiler numbers are inching up in one wheelpath, the profiler technician will tell the paving foreman. He in turn will check the 42-foot ski, and look at the augers on that side of the paver. When we see that something is off, we go through a whole trouble-shooting routine. It could be as simple as somebody bumping the 42-foot ski."
Conti says Lindy uses two 42-foot-long "over the screed" skis – in contact with the pavement – as mobile reference units to help control paving depth. The front part of the ski rides on the existing surface of pavement, and the rear portion of the ski rides on the newly-placed asphalt. "We have found that the contact method with over-the-screed skis gives us the best ride," says Conti.
Winners in the heartland
Des Moines Asphalt & Paving's most recent Hayes Award went for a three-mile stretch of Interstate 235 in Des Moines, IA. The contractor added a lane and a shoulder of full-depth asphalt to I-235, and paved three 2-inch lifts of asphalt on the adjacent two lanes of existing concrete. Then the entire width was paved with a 2-inch wearing surface running in both directions.
Base and intermediate course paving had to be coordinated with construction of a drainage sewer and median barrier in the center of the divided highway. That made placement of the intermediate courses more difficult, said Gene Baloun, paving superintendent.
A Six-Pack Astec asphalt plant supplied mix to the paver, which ran along at about 35 to 40 feet per minute; the plant could crank out 300 to 350 tons per hour. The contractor used a Roadtec SB 2500C material transfer vehicle for the intermediate and surface courses.
"We ran 13 trucks for the beginning and ending of every shift, during rush hour times for traffic," said Baloun. "It was about 10 miles from the plant to the site, and it took a little less than an hour for the trucks to make the round trip. Then in the middle of the day, we could back off to 11 trucks.