When a major interstate requires resurfacing, the efficiency of the milling operation often determines whether the entire project stays on schedule and within budget. For Gallagher Asphalt Corp., resurfacing an 8.5-mile stretch of I-57 in Kankakee County, Illinois, demanded a coordinated approach using three cold milling machines working in echelon. This method, where multiple modern cold milling and pavement removal machines operate in a stepped formation, allowed the contractor to achieve production rates of up to 25,000 square yards per shift while maintaining strict specifications for depth, grade, and surface texture.
The Operational Strategy Behind Echelon Milling on Interstate Projects
Echelon milling involves deploying two or more cold planers side by side or in a staggered formation to cover a wider total cutting width in a single pass. On the I-57 project, Gallagher Asphalt used a pair of new Wirtgen W 210 cold mills alongside an older W 2000 machine to cut a 16-foot-wide swath across the passing lane and shoulder at a depth of 4 inches. This coordinated approach is essential for interstate resurfacing because it minimizes the number of passes required, reduces overall machine hours, and produces a more uniform milled surface for the paver to follow.
How the Echelon Formation Works
The echelon setup on I-57 involved the W 210 machines cutting the 12-foot passing lane while the W 2000 handled the 4-foot inside shoulder. Earlier in the project, a W 210 had worked in tandem with a smaller W 120 4-foot machine to mill the 10-foot outside shoulder. The staggered arrangement allows each machine to work independently while contributing to a single, coordinated milling front.
Key advantages of the echelon approach include:
- Wider coverage in a single pass: Three machines working together can mill up to 20 feet or more of pavement width simultaneously.
- Reduced lane closure time: Fewer passes mean the operation clears each section faster, which is critical on interstates where lane closures are restricted to nighttime hours.
- Improved surface consistency: All machines mill to the same depth reference, producing a level surface that requires less remedial work before paving.
- Better logistics management: Trucks can be staged to service all three machines from a single loading zone rather than spread across multiple work areas.
Equipment Selection for High-Production Milling
The choice of milling equipment directly affects production rates and project economics. Gallagher Asphalt selected the Wirtgen W 210 based on a proven productivity improvement on earlier interstate resurfacing projects. The company reported that the W 210 boosted output from approximately 17,000 square yards per shift with a W 2000 to 25,000 square yards per shift, a gain of nearly 50 percent.
The W 210 is a dual-engine cold milling machine that generates 671 total horsepower and can be fitted with milling drum assemblies of 59, 79, or 87 inches working width. Its key specifications include:
| Specification | Wirtgen W 210 | Wirtgen W 200 |
|---|---|---|
| Engine configuration | Dual diesel engines | Single diesel engine |
| Total power output | 671 hp | 550 hp |
| Working width options | 59, 79, or 87 inches | 59, 79, or 87 inches |
| Maximum milling depth | 13 inches | 13 inches |
| Operating weight | 62,138 lbs | 59,934 lbs |
| Selectable engine speeds | 3 speeds | 3 speeds |
The dual-engine design of the W 210 provides a fuel-saving drive concept that allows operators to use only one engine for lighter milling tasks, reserving full power for deep or wide cuts. This flexibility is particularly valuable on interstate projects where milling depths and widths vary between the main line, shoulders, and ramps.
Mix Design and Material Management for Interstate Resurfacing
Beyond the milling operation itself, successful interstate resurfacing requires careful attention to asphalt mix design, plant logistics, and trucking coordination. The I-57 project used multiple Superpave mix designs tailored to different pavement layers and traffic conditions.
Superpave Mix Designs Used on I-57
The project specified four distinct mix types based on pavement position and performance requirements:
- Shoulder base course: 70-gyration Superpave mix with PG 64-22 liquid asphalt binder
- Shoulder surface course: 90-gyration Superpave mix with PG 64-22 liquid asphalt binder
- Main line bottom lift: 90-gyration Superpave mix with polymer-modified PG 70-22 binder for increased rut resistance
- Main line surface lift: 90-gyration Superpave mix with polymer-modified PG 70-22 binder and steel slag aggregate for enhanced skid resistance
The use of polymer-modified binders and steel slag aggregate on the main line surface course reflects the demanding requirements of interstate traffic. Polymer modification improves the binder’s elasticity and temperature susceptibility, reducing the risk of rutting in hot weather and thermal cracking in cold weather. Steel slag, with its rough surface texture and high angularity, provides excellent friction characteristics that help meet skid resistance specifications.
Plant-to-Paver Logistics
On the I-57 project, the asphalt plant began shipping mix at 6:40 p.m., with paving starting at 7 p.m. and continuing until approximately 5 a.m. The operation required 30 trucks to maintain a steady feed of mix to the paver, which placed asphalt at a rate of 350 tons per hour. All lanes had to be cleared and reopened to traffic by 6 a.m., leaving no margin for equipment breakdowns or logistical delays.
This tight nighttime schedule underscores the importance of reliable equipment and thorough pre-project preparation. As Jim Trost, Gallagher’s superintendent of operations, noted, having equipment in good condition is essential because a single shutdown can stop the entire operation. The company’s investment in newer, more productive milling machines directly addresses this risk by reducing the likelihood of mechanical failures during critical production windows.
Paver Selection and Screed Configuration for High-Speed Paving
After milling, the success of an interstate resurfacing project depends on the paving operation. Gallagher Asphalt used a Vision 5200-2 10-foot tracked paver equipped with a Carlson EZ-IV screed set to 16 feet wide, with screed extensions and auger extensions on the left side to cover the 4-foot shoulder.
Why Tracked Pavers Dominate Interstate Work
Gallagher Asphalt has standardized on tracked pavers across its fleet, operating two Vision 5200-2 10-foot machines and one Vision 5100-2 8-foot machine. The company cites several reasons for this choice:
- Versatility: Tracked pavers perform well on both stone bases and milled surfaces, eliminating the need to match specific machines to specific project types.
- Fleet standardization: With a uniform paver fleet, any machine can be deployed on any project, simplifying scheduling and reducing the number of pavers needed overall.
- Grade control integration: The Niveltronic grade and slope controls performed well across a variety of applications, from parking lots to interstate highways.
- Transfer device compatibility: Tracked pavers work effectively with material transfer vehicles and hopper inserts, which improve mix consistency and reduce material segregation on wide mat pours.
Screed Extensions for Variable Width Paving
The Carlson EZ-IV screed on the Vision 5200-2 allowed operators to pave the 12-foot lane and 4-foot shoulder in a single pass by using hydraulic screed extensions. This capability is essential for interstate work where the main line and shoulder must be paved simultaneously to ensure a seamless joint and consistent density across the full pavement width.
Operational Challenges and Best Practices for Nighttime Interstate Milling
Nighttime interstate resurfacing presents unique challenges that differ from daytime work on secondary roads. The I-57 project operated under a five-mile lane closure restriction, which limited how far the milling operation could advance ahead of the paver. This constraint required precise coordination between the milling and paving crews to maintain continuous production without allowing the gap between them to exceed the closure limit.
Crucial Considerations for Night Operations
Key factors that determine success on nighttime interstate milling projects include:
- Truck staging and cycle times: With 30 trucks servicing three milling machines and the paver, efficient loading and routing was critical. Delays at any single machine could cascade through the entire operation.
- Equipment redundancy: Gallagher’s preparation of equipment before the project start helped minimize the risk of breakdowns during the production window.
- Weather monitoring: Temperature and moisture conditions affect both milling performance and paving quality, particularly when working with polymer-modified binders that have specific temperature requirements.
- Traffic control and safety: With lane closures on a busy interstate, proper traffic control planning and equipment technology are essential for worker safety and public protection.
Cutting Edge Tips for Maximizing Milling Productivity
To achieve the highest possible production rates from cold milling machines on interstate projects, contractors should pay close attention to cutterhead maintenance and machine setup. Worn or incorrectly selected cutting tools reduce milling speed, increase fuel consumption, and produce a rougher surface that requires additional corrective work. Contractors who stay current with cutterhead tips and best practices for pavement milling cost reduction can significantly improve their bottom line on large-scale resurfacing projects.
Conclusion
The I-57 resurfacing project demonstrates how the strategic deployment of multiple cold milling machines in echelon formation can dramatically improve production rates on interstate highway work. By combining high-capacity equipment like the Wirtgen W 210 with careful logistics planning, appropriate mix designs, and standardized paver fleets, contractors can complete complex resurfacing projects within the tight constraints of nighttime lane closures. As highway agencies continue to prioritize pavement preservation and rehabilitation over new construction, the ability to execute efficient, high-production milling and paving operations will remain a competitive advantage for forward-thinking contractors.