How Shuttle Buggy Material Transfer Vehicles Help Contractors Earn Smoothness Bonuses on Asphalt Projects

Earning smoothness bonuses on asphalt paving projects demands more than a skilled screed operator and a well-calibrated paver. It requires a coordinated system that delivers consistent, uniform material without interruption or segregation. Material transfer vehicles (MTVs), particularly the Shuttle Buggy style, have become the tool of choice for contractors pursuing top-tier smoothness incentives. Eight of the last 10 winners of the National Asphalt Pavement Association’s Sheldon G. Hayes Award used MTVs on their award-winning projects. How Cold Milling Technology Helps Contractors Meet Smoothness shows another surface preparation technique that works alongside MTVs to achieve the ride quality that earns maximum bonuses. This article examines how Shuttle Buggy MTVs contribute to smoothness outcomes through case studies from real award winners.

The Role of Material Transfer Vehicles in Achieving Smoothness Specifications

State DOTs increasingly tie contractor compensation to ride quality measured by the International Roughness Index (IRI). When a paving crew delivers pavement below the target IRI threshold, the contractor earns a percentage bonus on tonnage placed. Falling short means forfeiting incentives or facing penalties. The Shuttle Buggy MTV helps contractors hit those targets by addressing three challenges: material segregation, paver stop-and-go, and thermal uniformity.

Eliminating Thermal and Physical Segregation

Segregation causes ride quality failures and density noncompliance. When hot mix asphalt cools unevenly or separates by aggregate size during transport, the resulting mat develops weak spots and surface irregularities. The Shuttle Buggy MTV remixes the asphalt in its auger-filled reblending chamber before transferring it to the paver. This restores homogeneity, eliminating thermal segregation (where load edges cool faster than the center) and physical segregation (where larger aggregate rolls to the windrow edges). Kyle Duininck, general manager of Duininck Inc. Texas Division, notes that the MTV prevents thermal segregation especially in colder weather. His company won 100 percent of allowable smoothness bonuses on its 2003 award project on U.S. 287 in Texas.

Maintaining Continuous Paver Operation

Every time a paver stops to wait for a truck, the mat cools, the screed settles, and a bump forms at the stop point. These bumps translate directly into IRI measurements that reduce bonuses. The MTV acts as a material buffer, holding several tons of asphalt to feed the paver while trucks cycle on and off the grade. Key benefits include:

• Elimination of transverse joints caused by paver stops
• Consistent paver speed throughout the shift
• Uniform mat temperature from start to finish of each load
• Reduced screed settling marks at restart points
• Higher overall production rates with fewer interruptions

Brandon LeFevre, general manager for Staker Parson Cos., reported that his crew ran at 300 to 325 tons per hour on the award-winning I-15 project. The MTV kept a full head of material in the paver, enabling the crew to lay 250,000 tons of hot mix asphalt in seven months.

Real-World Case Studies from Sheldon G. Hayes Award Winners

The Sheldon G. Hayes Award, given annually by NAPA, recognizes the highest quality asphalt pavement project in the United States. The selection process evaluates specification compliance, density, smoothness, and visual inspection through a two-year, three-step process. The historical record shows contractors who deploy MTVs consistently outperform peers on smoothness metrics.

Staker Parson: 65 Percent Smoothness Bonuses on I-15

Staker Parson Cos. of Salt Lake City won the 2010 award for 8.5 miles of Interstate 15 in Utah. The project required rubblizing three lanes of concrete in each direction, overlaying them with asphalt, and adding a lane on each side in the median. The design called for 7 inches of hot mix topped by a 1-inch open-graded friction course, placed as a 2.5-inch base followed by two 2.25-inch lifts.

Double-bottom belly dumps hauled asphalt to the grade in windrows. A Roadtec Shuttle Buggy MTV with a windrow pickup attachment collected the windrow, remixed the material, and transferred it to the paver. Gaps in the windrow caused by the pup trailers of belly dumps were bridged by the MTV without interrupting the paver. Staker Parson won 65 percent of smoothness bonus payments and 50 percent of material quality bonuses measured by binder content, gradation, and compaction.

Lindy Paving: Three-Time Winner Below 30 Inches Per Mile IRI

Lindy Paving Inc. of New Castle, Pennsylvania, has won the Sheldon G. Hayes Award three times, using a Roadtec SB 2500 Shuttle Buggy MTV on all three projects. The lowest smoothness incentive earned was 79 percent; the highest was 91 percent, on the 2009 winner. That project covered 6.6 miles of Interstate 79 north of Pittsburgh with 18 inches of hot mix asphalt over a cracked and seated concrete base.

Pennsylvania DOT set its smoothness bonus scale starting at 60 inches per mile IRI deviation, with maximum bonus at 35 inches per mile or less. Lindy hit 27.5 inches per mile on the northbound side and 29.2 on the southbound, as reported by quality control manager Joe Conti. Operations manager Dan Ganoe stressed maintaining consistent paver speed through each shift; the crew paved from bridge to bridge within a single shift, eliminating transverse joints entirely. Vince Tutino, president of Lindy Paving, called the MTV an absolute necessity for continuous paving, preventing trucks from bumping the paver, remixing to prevent segregation, and affording faster delivery to the paver.

Des Moines Asphalt: Conveying Mix Over Barrier Rails

Des Moines Asphalt and Paving Co., a two-time award winner, earned its 2006 award for three miles of Interstate 235 in Iowa. The project added a lane and shoulder of full-depth asphalt inside a temporary concrete barrier running the entire three miles. Greg Kinser, vice president, stated the MTV was a necessity because there was no other way to get mix into the narrow median. The crew ran the MTV along the outside of the barrier and conveyed asphalt over the rail to the paver. The MTV also improved production: Kinser estimated the contractor would have needed one or two additional trucks to pave at the same rate without it. Paving Superintendent Gene Baloun added that the MTV maintained enough material reserve to give leeway with truck arrivals.

Additional Award-Winning Applications

P. Flanigan & Sons Inc. of Baltimore won the 2007 award for 16.8 miles of I-97, working at night due to heavy beach-bound traffic. The company used an MTV for the entire project, with project manager Glenn Snyder noting it eliminated waiting for trucks. The project required 60,700 tons of hot mix. Norris Asphalt Paving Co. of Iowa won the 2001 award for County Route P46, placing 10.5 inches of full-depth asphalt over a rolled stone base. Brady Meldrem, president, said the contractor maximized its smoothness incentive and credited the MTV. He noted that by winning smoothness incentives and avoiding density penalties, an MTV can pay for itself within one project cycle.

How MTV Design Features Drive Smoothness Outcomes

The Shuttle Buggy MTV earns its bonuses through engineering features that directly affect final ride quality.

Windrow Pickup and Continuous Reblending

The windrow pickup attachment collects asphalt directly from a windrow deposited by belly dump trucks. The material is conveyed into the storage chamber, where augers continuously reblend the mix. This process eliminates the temperature differential between the surface and interior of a windrow, ensuring the paver receives uniform-temperature material across the entire mat width.

Continuous Paving Without Truck Interference

Traditional direct-dump paving requires trucks to back up to the paver, creating slowdowns and screed disturbances. The MTV breaks this cycle:

• Trucks dump into the MTV rather than the paver, eliminating truck-paver contact
• The MTV feeds the paver at a controlled rate from its own conveyor
• Windrow pickup mode separates truck logistics entirely from paver operation
• The paver maintains constant speed, the single most important factor for uniform mat density

High-Volume Delivery for Thick Lifts

Projects requiring thick lifts consume mix faster than a windrow of practical height can supply. Duininck explains that with a heavy volume of asphalt, it is impossible to dump a windrow heavy enough to keep the paver going. The Shuttle Buggy’s storage capacity allows high-volume material delivery over short distances, making it essential for lifts exceeding 3 inches. This proved critical on the Lindy I-79 project with 18 inches of total asphalt and the Norris P46 project with 10.5 inches of full-depth pavement.

Business Case for MTV Investment

Bonus Potential Compared to Equipment Cost

At typical state DOT bonus rates of 2 to 5 percent of contract tonnage price, a 90 percent bonus on a 60,000-ton project at $90 per ton represents a substantial return. Beyond smoothness, the MTV improves in-place density by preventing thermal segregation, reducing the risk of failing core-density tests that can trigger costly remedial work.

Production Efficiency Gains

• Higher throughput: Des Moines Asphalt estimated needing one to two additional trucks to match the same rate without an MTV
• Reduced crew size: Fewer coordination issues let the paver crew focus on mat quality
• Extended paving windows: Thermal segregation prevention allows paving in cooler conditions
• No transverse joints: Continuous paving from bridge to bridge removes the most common IRI spike source
• Faster completion: Staker Parson completed 250,000 tons in seven months via uninterrupted operation

Specification Trends Favoring MTV Use

Tutino noted that Pennsylvania’s segregation specifications effectively require a Shuttle Buggy, as the only reliable way to meet segregation limits at production scale is through continuous remixing. As more state DOTs adopt performance-based specifications tying compensation to IRI targets, equipment that supports those outcomes becomes less optional and more expected. Contractors who invest in MTV technology position themselves to compete for projects with aggressive smoothness specs that less-equipped competitors cannot profitably pursue. Micromilling Techniques for Achieving Smoothness Bonuses in Asphalt covers the complementary surface preparation that prepares existing pavement for the uniform mat the MTV helps produce. Training and Advanced Paver Controls Deliver Smoothness Bonuses addresses the operator expertise and machine automation that combine with MTV material handling for maximum bonus outcomes. New Racking Criteria for Asphalt Shingle Roof Systems provides relevant context for professionals managing asphalt-related construction standards across applications.

The Shuttle Buggy MTV is not merely an equipment option. It is a documented, repeatable method for achieving the uniform material delivery, consistent paver speed, and segregation-free mat that smoothness bonuses reward. As Vince Tutino said, it is a necessity.