Paving precision: Navigating the path to pavement quality control

From education to construction engineering, creating a good foundation is the first step for future success. For urban planners, roadways are a critical part of keeping communities connected and helping establish desirable traffic patterns. Before these roadways can be enjoyed, they need to be built and maintained. Proper street paving ensures the safety of drivers and pedestrians alike. 

Once community plans are drawn, contractors must put down asphalt mix to create resilient streets that can withstand continual use and changing or harsh climates. However, one major challenge of infrastructure paving is maintaining an even mixture of asphalt with uniform temperature throughout. It is also important that asphalt is rolled out and layered effectively by flattening and smoothening the asphalt based on the conditions of each site.

Ineffective rolling patterns, weather conditions or improper handling of materials can cause variations in an asphalt mix. These inconsistencies can cause irregular compaction, affecting one of the key asphalt pavement construction quality characteristics, known as in-place density.

Non-uniform in-place densities accelerate road deterioration and decrease the lifespan of asphalt pavements. What starts as a thermal non-uniformity transforms into cracks, rutting and potholes- ultimately resulting in costly repairs for communities and drivers.

To help ensure more resilient roadways, the quality of asphalt pavement is assessed at the end of the project in a pass/fail test of construction criteria. Failure can mean having to redo the project, effectively ruining budget plans and deadline projections.

Hasan Ozer, an associate professor of civil, environmental and sustainable engineering in the Ira A. Fulton Schools of Engineering at Arizona State University, says construction quality impacts everyone in a community.

“Transportation infrastructure is the highest value asset of all states and local governments,” Ozer says. “It’s one of the biggest investments a city can make for its citizens.”

Ozer and his team in the School of Sustainable Engineering and the Built Environment, part of the Fulton Schools, are developing a cost-effective technology to advance quality control methods for contractors to correct irregularities before the pavement’s fate is set in stone.

Paving paths for intelligent compaction

Ozer’s Pavements Analysis Laboratory team set out to identify and quantify these irregularities by collecting thermal and density metrics throughout the paving process. They are also using image analysis techniques combined with artificial intelligence to provide instantaneous updates to the contractors.

“Giving real-time feedback to the contractor provides tremendous value in terms of time, money and quality,” Ozer says. “The pavements last longer because irregularities are managed before they can affect the pavement.”

Previous industry standards used stationary thermal sensors with narrow viewpoints and limited analysis, or expensive handheld devices with limited reach.

In his study, sponsored by the U.S. Department of Transportation’s National Center for Infrastructure Transformation, Ozer is bypassing stationary sensors by equipping an unmanned aerial vehicle, known as a UAV or drone, with thermal sensors to track non-uniform pavement cooling over time. The team is also developing software to analyze the data and provide real-time feedback to contractors who can access it through a phone app. 

By generating opportunities for intervention, construction crews can assess if pavement irregularities can be managed by changing rolling patterns or adjusting their equipment and materials transport method.

Tim Murphy, president of the forensic engineering company Murphy Pavement Technology, says the methodology will accelerate the quantification of physical and thermal segregation.

“You have to know what you’re looking for,” the forensic engineer says. “These problems require speedy identification and quantification to lead to a solution. Ozer and his students are doing a remarkable job with this research, which is close to becoming an implementable tool that will save agencies across the nation millions of dollars.”

After completing the first phase of the study and successfully presenting the work at the annual conference of the Transportation Research Board, the team plans to expand its technology to generate models and guide construction crews to achieve optimal uniform asphalt layering by also tracking the rolling process.

“Tracking rollers with the drone is a unique application that no one else is doing,” Ozer says. “We are working on advanced artificial intelligence models to identify rollers and monitor their movements as they operate on the freshly paved mat. Our ultimate goal is to combine thermal data with roller movements and give contractors real-time feedback about their asphalt paving techniques.”

Taking the research to the streets

Having secured promising results across the greater Phoenix area, Ozer is now partnering with the city of Mesa, Arizona, and M.R. Tanner Construction, one of the largest and most experienced paving companies in the Valley, to apply his quality control methodology to active residential construction sites.

The test site installation was devised by Southwest Pavement Technology Consortium, ASU’s hub for pavement innovation that connects researchers, industry members and industry partners to maximize the impact of various research areas of experience to real-world projects.

In addition to testing and developing UAV-assisted construction quality assessment protocols, the project will also investigate the long-term aging impacts of extreme summer heat on Arizona’s pavements and evaluate the efficiency of two different coating technologies used to slow down the adverse effects of pavement fatigue.

In an extensive test of quality control, construction crews from M.R. Tanner Construction will use the research team’s technology to test their work while comparing information gathered from the on-site testbeds equipped with thermal sensors to confirm the drone’s data.

City of Mesa Pavement Management Supervisor Matt Manthey says the endeavor will help them extend the lifespan of the city’s roadways and maintain safer and smoother roads for the public.

“We jumped at the opportunity to partner with ASU,” Manthey says. “The city of Mesa enjoys helping our academic partners here in the Valley of the Sun.”

The M. R. Tanner Construction crew is paving a residential neighborhood in Mesa, Arizona, using Ozer’s imaging methods. Image courtesy of Hasan Ozer

Left: Thermal image of the construction crew during the paving process. Right: RGB image of the construction crew during the paving process. Images courtesy of Hasan Ozer

The test site will be revisited routinely over the next two years to assess pavement fatigue.

“I hope to apply the same concept in other projects with other state and local agencies,” Ozer says. “These field projects are a great way of testing innovative ideas and accelerating the implementation of research into practice, as well as great learning opportunities for our students to observe construction processes and interact with the frontline workers.”

Underpinning industry success

The collaboration is a major step in confirming the technology’s accuracy and capacity to be integrated into various construction sites.

Dominick Martinez, who oversees business development at M.R. Tanner Construction, says the industry needs creative solutions like these to ensure quality.

“The technology has given our team another tool in our toolbox,” Martinez says. “M.R. Tanner Construction is always looking to improve. Having an open mind to new technologies will make us a better company and help us provide quality service to our customers.”

Murphy, who applies his years of experience in forensic engineering to train future engineers, says the technology has already yielded impact as training material on asphalt workmanship for contractors and is being used in curricula for contractors, consultants and transportation agencies in multiple states.

Ozer says the ASU community reinforces collaborative relationships through resources such as the Southwest Pavement Technology Consortium and Skysong Innovations, the university’s technology transfer arm that helps researchers find commercial pathways for new endeavors.

“ASU’s ecosystem is very friendly to implementing or developing innovative tech and securing researcher’s rights in those technologies,” Ozer says.

Ozer is in talks with major contractors and construction equipment manufacturers to support his research as he paves the way for contractors to achieve quality control, decrease costs and condense timelines.

“The collaboration between ASU, the city of Mesa, M.R. Tanner Construction and other consortium partners is a true testament to how working as a team will make us all better,” Martinez says. “It’s our responsibility as leaders in the industry to make sure that we provide the best possible product for the people.”

The full research article, Thermal Profiling of Asphalt Pavement Construction Using Unmanned Aerial Vehicle, is published in the Transportation Research Record (TRR) journal.