It may very well be the smoothest 10 miles of interstate highway in the state of Montana and maybe even in North America. Heck, it might be the smoothest chunk of highway on the globe, if you talk with those involved.
A recently renovated 10-mile section of I-90, starting in Alberton, Montana, which is located on the western part of the state near the Idaho border, and stretching east, received sterling commendations, shattered target IRI scores, and earned the general contractor $605,000 in quality bonuses. It even won the 2014 MCA Excellence Award for Best Paving Smoothness from the Montana Contractors Association.
“Our crew, subcontractors, and the Montana Department of Transportation (MDT) inspectors all worked seamlessly together giving us the efficiency, thoroughness, and quality results we were after,” states Lance Streeter, general superintendent with Knife River Corporation’s Western Montana Division, headquartered in Bismarck, North Dakota. “This was a 2-year project that we finished in one construction season.”
THE PROJECT
Knife River Corporation was the general contractor on the $15.5 million I-90 renovation. The company has 5,000 employees during peak season and operates in 18 states with physical locations in 14 of them. The company had eight employees assigned to the road project.
The I-90 project commenced on June 10 with Knife River’s subcontractor Industrial Builders, Inc., performing the shoulder-to-shoulder rotomilling of the road to 3/10 of a foot, with the milled material converted to reclaimed asphalt pavement (RAP). The drive lane and passing lane were milled out an additional 3/10 for a total of 6/10 of
a foot.
SMOOTH PAVING
As Industrial Builders began completing the 40 lane miles of milling, Knife River could begin paving.
“When we first looked at this project, I knew we had to be aggressive in our work schedule and that we had to achieve consistent smoothness with each lift that we placed,” Streeter says. “The payment incentives that MDT offered were very attractive and within our capabilities to achieve.”
The bonus incentives offered by MDT were based on achieving paved finished surfaces with favorable International Roughness Index (IRI) scores:
- 45 – 55 IRI was acceptable—no bonus, no penalty
- 35 – 44 IRI earned up to 24 percent bonus, based on a sliding scale
- below 35 IRI earned a 25 percent bonus
“I knew that in order to achieve a low IRI index throughout the job that we needed continuous paving with thoroughly mixed hot-mix asphalt (HMA) at the right temperature,” states Streeter. “I knew that in order to achieve that we’d need to use a Shuttle Buggy.”
MATERIAL TRANSFER VEHICLE
Knife River owns three Roadtec SB-2500e/ex Shuttle Buggy material transfer vehicles (MTV) that are designed to store and transfer HMA material to a paver to enable continuous paving production. A patented anti-segregation auger remixes materials just before delivery to the asphalt paver.
“The Shuttle Buggy was instrumental in ensuring continuous paving and it reduced our trucking costs since the trucks could dump their loads and return to the plant, which was located about 23 to 28 miles away,” says Streeter.
Streeter continues, “When you look at temperature change and segregation issues that can occur during a 30-minute haul, it’s easy to see how the Shuttle Buggy helps. With its 25-ton surge capacity, we had plenty of mix to feed the paver and keep it continuously productive. This meant our belly dump train could unload and leave right away.”
Knife River used a two-dump-truck train for asphalt hauling. The lead belly dump had a 26- to 28-ton capacity and the connected pup had a 12- to 14-ton capacity. The Shuttle Buggy used a windrow pickup head to add the hauled HMA to its dump hopper.
PROJECT COMPLETED
The Montana I-90 rehab project required a total of 165,000 tons of HMA with approximately 1/3 of that being RAP. Knife River placed three lifts.
The project required cooperation and coordination to maintain uninterrupted paving. In addition to the steady delivery of HMA from the asphalt plant, there was the removal and replacement of 60,000 lineal feet of guardrails.
“Our sub, Mountain West Holding Company, based in Missoula, Montana, had all six of their punch trucks working,” Streeter says. “They did an incredible job of pulling guard rails in front of the paver and then replacing them after the paver—it was poetry in motion.”
The Montana I-90 project, which started in June, was completed October 28—a full year ahead of schedule. In addition to an early completion, Knife River Corporation also achieved an average IRI index score of 29, which gave the company the highest incentive payment for finished pavement smoothness. For its efforts, Knife River earned $605,000 in bonuses. ■
About The Author: Jeff Winke is a business and construction writer based in Milwaukee, Wisconsin. He can be reached through www.jeffwinke.weebly.com.
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Modern Contractor Solutions, May 2015
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