Message from the Director

The Long and Winding Road

The Beatles’ The Long and Winding Road is one of my all-time favorite songs, partly because it’s about a road—at least, sort of. Sir Paul’s melancholy lyrics and tune uses the road as a metaphor for the journey of life through strife, sorrow, and loneliness back to a familiar path and destination.

Research is often a long and winding road, and sometimes it’s a dead end. The real joy of research is seeing a new technology make its way into mainstream practice. NCAT has been fortunate to play a significant role in the development and implementation of several asphalt pavement technologies through the past three and a half decades, and it’s gratifying to see the success of technologies like the ignition method, stone-matrix asphalt, PCC pavement rubblization, thinlay mixes, and warm-mix asphalt that have been accepted into day-to-day usage across the country. NCAT doesn’t deserve all of the credit—in some cases, our primary role has been to facilitate implementation through training.

Research and development of new technologies generally progress through numerous stages. In the world of asphalt research, some of the major steps include initial proof-of-concept lab testing, designed experiment lab-scale testing (typically to refine formulations and/or dosages), further lab testing to evaluate interactions with a broader range of mix components, plant trials, accelerated field testing, and construction and evaluation of field test sections. In some cases, it is also necessary to conduct studies along the way to make sure there are no harmful effects to workers and the environment.

It takes a long-term view with perseverance (and usually a big stack of Benjamins) to take a technology from the genesis of an idea all the way to implementation into routine use. Often, we’re just not sure if the investment is worth the change from the status quo. A truly valid cost/benefit analysis of a new technology can’t really be conducted until we have data about its effect on long-term performance and the full cost of the technology. Unfortunately, it typically takes half of a career to really see the impact of some changes.

Some researchers fall into the habit of referring to the results of lab tests or model predictions as “performance.” True performance is what happens on the roads, highways, and airfields under real traffic and years of environmental exposure. When trial projects are built on real highways, the pavement research community typically only examines field performance for just a few years. That’s not nearly long enough to quantify the full impact of a technology to determine if it really pays off. This is where the benefits of accelerated pavement testing really shine, especially accelerated pavement testing that involves the real impacts of aging. On the NCAT Test Track, we apply 16,000 axle loads (up to 20-kips) every day to achieve four times the loading of a “typical” interstate highway. We’ve learned that the environment also has profound impacts on how a pavement responds to loading through daily and seasonal changes in precipitation and temperatures that affect asphalt pavement stiffness, as well as aging effects that take years to manifest an impact on surface layers.

There are very few shortcuts we can take to prove out new pavement technologies. But with good experiments, documentation and a little patience, we are developing better tools to get us where we want to go faster, and possibly, make the long and winding road a little shorter.

Randy C. West, Ph.D., P.E. | Director & Research Professor