Friday, June 5, 2020

The AASHO Road Test: A Breakthrough in Pavement Technology

The 1950's were an incredibly transformative time in American transportation, with the passing of the Federal Aid Highway Act of 1956. Driving on I-80 through Central Illinois, you will pass a sign that offers only a small clue of just how expansive this shift was, showcasing one of the many pieces of building our highways, the pavement itself.

Perhaps you underestimate the amount of engineering and science that pavement materials go through, and this test is a great example of this in action, when the stakes were extremely high, as the largest road expansion in history was in its infancy.

Starting in 1956, AASHO, the predecessor to today's AASHTO, began a $27 Million project tp study different pavement materials, and the impacts that traffic would have on those materials.

Image: Google Street View
The AASHO Road Test was instrumental in scientific breakthroughs on how pavements responded to traffic load, weights, climate impacts, and how long pavement would last. 

Before I-80 was built, the Test Road was a loop as described below:

The AASHO Road Test: Report 1, History and Description of the Project.  Special Report 61A.  Highway Research Board, National Academy of Sciences.  Washington, D.C.
Between 1958-1960, actual tests were conducted at the site using different kinds of vehicles. By the time the test was done, the straight sections of the track were incorporated into the design of I-80. 

In addition to the sign, a small track of pavement is preserved at the site.

Google Satellite Imagery. The loop is located a few miles west of Ottawa on the south side of I-80.
The results and information derived from the Tests cannot be overlooked, as the design of pavements and bridges on the Interstate Highway System largely followed its result. There are many roadside curiosities out there, but this one is one of the most interesting when it comes to the design of roads themselves. Unfortunately, there's no way to visit this site, outside of driving adjacent to it at 70 mph. 

Thanks as always for reading!

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