While Oregon Mainline Paving's typical bread-and-butter work is tied to mill and fill projects, the McMinnville, OR-based contractor recently completed a $25-million four-mile bypass around the City of Redmond and the traffic-free work zone proved beneficial in meeting project smoothness specifications.
The total $90.4-million project, delivered in-house by Oregon Department of Transportation Region 4, included constructing an irrigation canal, building bridges, moving Redmond's main power substation, and realigning U.S. 97 to bypass the business district.
The bypass runs between the Central Oregon Irrigation District's Pilot Butte Canal and the BNSF Railroad on the east side of Redmond, from just north of Veteran's Way on the south end to just south of O'Neil Highway junction on the north end.
With an average daily traffic count of 35,000 vehicles (12 to 15 percent being trucks) on the Redmond portion of U.S. 97, the project increases the north/south highway capacity and reduces congestion and travel delays on the Fifth/Sixth interchange in downtown Redmond.
The new alignment will improve freight mobility and freight access to future industrial developments in Redmond, while minimizing the number of heavy trucks traveling through downtown.
As the general contractor on the highway realignment portion of the project, Oregon Mainline Paving was charged with the construction of a divided four-lane full-depth asphalt roadway.
As a contractor specializing in heavy highway construction and road building, approximately 50 percent of the company's annual $40 to $60 million in revenue is self-performed paving work. Thirty percent of Oregon Mainline's revenue is tied to work performed by subcontractors (bridge work, striping, guardrail, etc.); and the remaining 20 percent is tied to earthwork.
With 90 percent of its work generated by ODOT, Oregon Mainline Paving uses most of the approximate 500,000 tons of HMA it produces annually to support its own crews working on those projects. With three portable plants, the contractor is equipped to travel the state to work on ODOT projects.
U.S. 97 project
According to Matt Seehawer, general manager for Oregon Mainline Paving, the contractor moved 463,000 cubic yards of embankment, installed 10,000 feet of drainage pipe and placed 140,000 tons of aggregate (basalt rock) base before actual paving could begin.
"The only challenge we faced during construction related to the drainage ability of building the new road over the solid rock conditions that exist in this part of the state," Seehawer says. "We were able to use cinder (basalt/volcanic) rock to construct the aggregate base and that provided the drainage we needed while allowing us to achieve a compacted subbase."
Along with being a major project for Oregon Mainline Paving, the Redmond U.S. 97 realignment also proved to be an ideal paving project to execute.
"We typically place approximately 240,000 tons of asphalt annually on mill and fill projects, along with a couple of major interchange projects (like the Redmond U.S. 97 realignment)," Seehawer says. "So this was a significant project for us and without traffic to contend with, it allowed us to maintain an aggressive construction schedule."
With a new 10-inch aggregate base and 10-foot concrete median barrier in place, the contractor's paving crew took over in placing approximately 110,000 tons of ODOT Level 3 12.5mm dense-graded Superpave hot mix asphalt to construct an 11-inch-thick perpetual pavement structure.
The full-depth asphalt surface design was specified by ODOT based on life cycle costs, location and usage.
According to John Heacock, Region 4 technology center manager, asphalt is generally specified on projects in Central Oregon (east of the Cascade Mountain Range) because it has performed well on roads that are subjected to studded tires in the winter.
The pavement was placed in four lifts, with the three 3-inch base/binder courses consisting of a PG 64-28 AC, ½-in. aggregate dense mix with lime additive to prevent stripping. The top 2-inch wearing course was produced with a PG 70-28 AC binder, ½-inch aggregate and lime additive.
"The contract called for a rich mix design (6.5 percent) and an anti-stripping agent (lime)," Seehawer says. "We were also allowed to use up to 30 percent RAP (reclaimed asphalt pavement) in the mixes we produced and placed; but since we were constructing a new road, we didn't have a RAP resource and had to go with all virgin materials."
Since the U.S. 97 project was a new road, the contractor's crews had the luxury of working without the traffic challenges normally associated with a typical mill and fill project.
"We had as many as four different pavers (Blaw-Knox) on the project at any given time, allowing us to pave in echelon," Seehawer says. "Paving in echelon not only allowed us to increase production, but also allowed us to achieve better longitudinal joints, especially between the two mainline travel lanes and do so using only three or four (IR) double-drum vibratory rollers."
Without traffic concerns, paving crews were also able to extend screeds to hot-lap turning lanes and other expanded areas, which eliminated longitudinal joints in the process. Along with the two 12-foot-wide travel lanes in each direction, the paving crews also constructed a 10-foot-wide outside shoulder and a 7-foot-wide inside shoulder along the concrete barrier.
To feed the echelon paving process, the contractor used belly-dump trailer trucks to deposit windrows of HMA in front of pick-up machines that transferred the mix into the paver hoppers.
"We were using a portable CMI counterflow plant with a 100-ton storage silo to supply our paving crew," Seehawer says. "That plant can crank out as much as 450 to 500 tons per hour; and on days where we were placing our mainline (travel lanes) lifts, we were laying 4,500 to 4,800 tons in a 10- to 10.5-hour shift."
The resulting smooth ride
Paving in echelon not only allowed Oregon Mainline Paving to maximize production, but to do so in a way that also produced the smoothness requirements the project outlined.
Using a profilometer, ODOT established a smoothness price adjustments based on a Profile Index of acceptable smoothness deviations in specified sections (mm/km or inch/mile). The contract allowed a price adjustment based on the results of the Profile Index (PI) for each 200 m (1/10th mile) segment.
The price adjustment applied only to wearing course material placed in the travel lanes of the project.
The price adjustment was applied to the contract unit price for Level 3 12.5mm dense lime treated HMAC and PG 70-28 asphalt in lime-treated HMAC. If the paving contractor achieves fewer than 3 inches per 1/10th mile of smoothness deviations, the smoothness price would be adjusted by +5 percent.
"We achieved full bonus on the job for ride smoothness and density requirements," Seehawer says. "Our ride smoothness numbers came in below the allowed deviation spec to receive the additional 5 percent and we hit the required 92 to 93 percent density requirement."
For Oregon Mainline Paving, meeting the smoothness and mix quality requirements of the project represented approximately $250,000 in additional bonus pay.
"In a competitive market, bonus pay is crucial to the overall profitability of company," explains Seehawer. "You have to submit a tight bid to get the job, but then you have to deliver the job to the customer's expectations in order to make a profitable return on your investment. It's just the nature of bidding and building government agency projects and we're proud to be one of ODOT's leading contractors."