In 1956, AASHO (predecessor to AASHTO) set up 7 miles of pavement loops and strips along the path of what is now I-80 in the center of Illinois, each consisting of a multitude of different pavement compositions. Most of these were intended to test pavement deterioration under repeated, carefully controlled truck loading, and were either later removed or paved over into the modern freeway. For whatever reason, the one test loop set up to test only the effect of weather, not truck loading, was allowed to remain and the freeway was built just to its north. Maybe they were still monitoring it at the time they were building I-80. Anyway, it's now accessible off the frontage road just west of Ottawa.


Looking east along the northern part of the loop. The outcome of all of these tests was the basis of the Load Equivalency Factor and other pavement wear data still commonly used in pavement design over 50 years later.


Looking west from the same spot.


Now looking east on the southern part of the loop. This was almost certainly a different pavement than where I was standing before, and walking around the loop probably yields others.


Looking west from there.


It said "non-destructive," but the weather can destroy over time as well. Watch your feet on the rebar.

Onto I-80
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