The Kensington Expressway . . . it’s called the “Gateway to the City of Buffalo.” It’s the section of Highway 33 that stretches from the Buffalo Niagara International Airport and leads drivers to downtown Buffalo, N.Y. From Rte. 198 to Dick Road, this portion of the Kensington is heavily traveled and congested during rush hour—bumper-to-bumper from 7-9 a.m. westbound and 4-6 p.m. eastbound—and the road was in need of repair.
However, major reconstruction and expansion is not planned for nearly six years, with funds coming from the recently signed SAFETEA-LU road bill. Michael Lydle, P.E., of the New York Department of Transportation (NYDOT) needed to find a way to improve the roadway and make it last for at least six years until the scheduled major reconstruction.
“The work we are doing now is part of a beautification project for the highway,” said Lydle, resident program engineer, North Erie County Region 5. “We are improving the road surface to offer a better ride for the 98,000 vehicles per day traveling the highway.” If the project lasts as planned, it will prove to be a very cost-effective method for maintaining nearly 21 lane miles of highway for the NYDOT.
Ultra-thin first
Highway resurfacing started with Donegal Construction Corp., Greensburg, Pa., milling a thin section of the road’s surface. The milling specialists had two projects in the area, Highway 33 and another on Grande Avenue leading to Niagara Falls. Two Terex CMI PR600 millers pulled double shifts, working in tandem on one project during the day and the other at night.One of the projects required the use of a fine grind cutter, so the contractor used the same cutter on both jobs. “It was more efficient and just as cost effective for us to leave the fine grind cutters in the millers,” explained Don Pfeifer, vice president of Donegal. “With the fine cutters, the PR600s were able to give us the production rate we needed on both jobs.”
The milling machines left behind narrow 1?4-in. grooves in the road, which allowed the milled lanes to stay open to traffic while waiting for resurfacing. With an 86-in. cutting width, the 600-hp machines quickly milled and profiled the road at an average 3?4-in. depth, leaving Highway 33 ready for the ultra-thin surface. More than 11,000 tons of millings were collected from the Kensington project for recycling. When the time came for resurfacing, Lydle chose a mix design that included a polymer-modified PG 68-24 asphalt binder with a very small 6.3-mm (0.25-in.) top aggregate size. This new, closed-graded design is being used in only two projects this season in the state of New York, and this is the first application for the new mix. “Using a polymer-modified binder is not new, but we’ve never used it in an ultra-thin application,” commented Lydle. “We chose this mix for cost, low noise and high friction.”
With such a high volume of daily traffic and congestion on Highway 33, Lydle also is counting on this mix to be rut-resistant. Lydle said it’s a calculated gamble, but he expects the service life of the road to last until it is scheduled for complete reconstruction.
Paving in tandem
For the surface overlay, Orchard Park, N.Y.-based paving contractor Holmes & Murphy Inc. doubled the amount of equipment to pave the road. While working with the test strips to determine the best rolling pattern, the paving contractor, with its 90 years of experience, quickly discovered that the new mix was difficult to handle. “The mix cools quickly and is difficult for the crews to hand work,” explained Richard Holmes, president of Holmes & Murphy. “We also found that we achieved better joint densities if we didn’t let the joint cool.”The paving contractor determined the best way to achieve spec densities would be to pave all three traffic lanes at one time. Therefore, the heavily traveled highway would have to be closed in one direction during paving so the surface had to be laid at night.
The NYDOT agreed to close portions of the Kensington in one direction from 9 p.m. to 6 a.m., leaving the road to Holmes & Murphy. “Everything had to be done by six in the morning—paving, compaction, cooling and striping—so the road could be reopened to commuter traffic,” said Holmes.
Paving started and stopped at bridges, splitting the project into quadrants, so as not to leave any cooled joints. Holmes & Murphy pulled the asphalt mix from Buffalo Crushed Stone’s Clarence Street plant, which left about a 20-minute drive to the jobsite. Target paving temperatures for the 3?4-in. lift were approximately 265 °F.
Two Terex Cedarapids rubber-tire pavers, the CR551 and CR552 Remix, led the paving trains. This is not the first time that Holmes has called on his Remix paver for work in this area. Just last season, the contractor used the CR552 Remix to pave the runways and taxiways at the Buffalo Niagara International Airport less than a couple of miles down the road. Both pavers were equipped with Terex Cedarapids Stretch 20 diesel screeds capable of paving widths from 10-26 ft with extensions. Holmes & Murphy set paving widths for both pavers at 18 ft, laying one-and-a-half lanes each.
This enabled the crews to take care of the full 36-ft-wide highway in a one tandem pass. The pavers stayed within 300 ft of each other, so the joints would not cool. This also positioned the joint in the middle of the center lane, so car tires, for the most part, would straddle the joint.
Tandem paving at the wider widths did not allow the paving crews to establish a continuous paving process, so occasionally the pavers would remain idle while waiting on the next load of asphalt. With screed assist, the screeds helped to maintain mat smoothness, even while the paver was stopped. This unique feature eliminates screed settling during a stoppage and the potential surface irregularities.
Bomag BW202ADH-2 and Ingersoll-Rand DD130 tandem vibratory rollers provided breakdown rolling of the ultra-thin mat. Due to the thin, 3?4-in. lift only two breakdown passes were necessary—working in vibration mode towards the pavers and static out. These rollers were on the mat almost immediately, compacting at 250°F. A final static pass was made by the finish rollers between 190-200°F before moving on to the next section.
Specified minimum mat densities were 94% of the 100% density target number (149). Anything registering below a 140 would cost Holmes & Murphy bonus money. When tested at the assigned 160-180°F temperature range, mat densities averaged mid 140s, easily passing spec.
Golden gateway
Through a coordinated effort between the New York DOT, Holmes & Murphy, Donegal Construction and Buffalo Crushed Stone, the citizens of and visitors to the city of Buffalo have a new, smoother road surface to make their daily commute. This beautification maintenance project also doubles as a permanent fix until further reconstruction takes place years down the road.This creative project saved commuters delays during resurfacing, as the entire job was completed in less than two months. More importantly, through the use of this new polymer-modified, ultra-thin mix design, the DOT was able to save the taxpayers money. “We were able to resurface nearly 21 lane miles for only $1.4 million,” said Lydle. “The cost would have been significantly higher if we used another approach.”
