WAPA: In July you presented at NAPA's midyear meeting about the Illinois Tollway's implementation of innovative processes and technologies for constructing and maintaining pavements. Could you please summarize the most recent findings you discussed?
The Illinois Tollway started its research program in materials in the mid-2000's to help make pavement better -- at lower costs and with equal or improved performance. As a customer-funded organization, the Tollway focuses on high-value research projects with a high likelihood of success and that can be implemented to make a real difference for drivers.
As the Tollway implemented technology innovations, its management and executives sought out a formal quantification of the benefits, asking, "What was the value of the research?" The Tollway and its consultants calculated the cost savings associated with research and innovation, and found that from 2004 to 2015, the Tollway saved $219 million related to aggregate, asphalt and concrete materials.
What are some of the innovations that are making a difference for asphalt pavements?
Steve's article talks about the testing and expanded use of green technologies: ground tire rubber (GTR), fractionated reclaimed asphalt pavement (FRAP), and recycled asphalt shingles (RAS).
Another key from a design perspective is to avoid over-designing and over-building. The Tollway has worked toward putting the right amount of the right materials into the right part of the pavement.
Hand in hand with that is not prescribing mixes in terms of specific materials. Instead the Tollway leaves it to contractors to select the aggregate, binder and modifiers that will meet stated performance requirements. There are often different but equally valid solutions to achieve rutting or cracking properties or to avoid draindown.
Are there any other emerging asphalt pavement technologies you can tell us about?
Two come to mind. First is dry-process ground tire rubber, where the rubber is added into the asphalt mix at the plant rather than into the asphalt binder at the terminal. This just-in-time use of GTR puts more control into the hands of the asphalt contractor and may end up changing the economies of when and how best to use this modifier.
Second is a project that the Tollway is doing with the University of Missouri to formalize a performance-related specification for asphalt mix designs. Without a national framework to go on, the Tollway is forging ahead in this area, and hopefully the results will be useful to other agencies as well.
Saving money without sacrificing pavement performance is a common theme here in Wisconsin. Often a road authority will be interested in trying something new but will have concerns about performance. What would you say to them?
"Analysis paralysis" is all too common in transportation research, and sometimes you just have to stop studying and start doing.
Steve Gillen has been instrumental for getting new technologies out into the field as a way to make roads better; I can't credit him enough for his vision and follow-through.
There are ways to be smart about it. Start small, on a shoulder or test section. Rather than using a new mix on a surface course,
try it on a less sensitive layer that isn't directly exposed to traffic or weather extremes.
This is how the Illinois Tollway came to be a leader with high-recycled pavements, building pavements with over 50 percent FRAP when other agencies were at the 15 percent range. The Tollway was also an early adopter of stone matrix asphalt (SMA), which has led to an average increase in life of three years, as well as other long-life designs. There's a stretch of perpetual asphalt pavement on I-90 just beyond the Wisconsin border built by Rock Road Companies and William Charles Construction in 2008 and 2009 that is performing beautifully, and it looks like it will perform beyond its originally scheduled mill and fill at 15 years age.
Thanks for sharing this information. We are excited to have you present to our members and customers at WAPA's annual conference in November.
Thank you for inviting me. I look forward to continuing this conversation in Madison.