Ottawa Test Loop

Its hard to pay attention to the brown "point of interest" signs on the highway nowadays. We're usually whizzing past them attempting to avoid the droves of distracted drivers playing with their GPS, reading a John le Carré novel, shaving with a USB-powered Norelco and drinking a Sobe life water while hunting for the hottest song on their iPhone 5 this week. Having recently spent some time up north with my family for Thanksgiving, Sarah and I once again passed the AASHO Test Road Site sign just outside of Ottawa, Illinois on Interstate 80. For years we have passed this marker and wondered what it stood for. It had to be a test road area for asphalt or cement we thought. We'd both take turns guessing what the AASHO acronym stood for. American Asphalt Society of Highway Officials? How about the Amalgamated Asphaltian Supporters for Huge Opportunities?

That game got old pretty quick.

A cursory internet search produced no information until very recently. Like this morning. After learning about the Ottawa test road's history and the important role Illinois played in the development of the pavement we drive (distracted) on every day, I thought it would be neat to share it here.

In reality the acronym stood for the American Association of State Highway Officials. The group got its start back in 1914 as a non-governmental organization that set standards for how roads and highways were designed & built. In the 1970's, the group incorporated the word "transportation" into their name since they also had a hand in various other forms of travel. As the U.S. was gearing up for the construction of a large interstate highway system, the AASHO wanted to ensure that engineers, government officials, and contractors had the information they needed to lay down a product that would hold up for decades. They also wanted to use that data to inform the government on how much money it would cost to maintain such a vast infrastructure so that they could adjust the gasoline tax rates accordingly. Then came the questions. What was the best type of concrete mix for heavy loads? What type of road bed created less rutting over time? What methods of patching cracks worked well?  These were just a few of the questions that the AASHO had, and the answer to those questions was the Ottawa Test Site.

The plan for the test road site was sketched out by the AASHO team and was bordered by US Route 6 to the south, and nestled between Illinois Route 178 in Utica and Illinois Route 23 near Ottawa. The configuration would call for six test loops over a seven mile stretch of virgin farmland. Different loops would be subject to various tests of actual vehicular traffic over a two-year period.
 

Construction of AASHO Test Track. Circa 1956.

Construction began in August of 1956 and the various loops were assorted in size, application, and building method. Some sections used an asphalt mix, while others were straight concrete.  There were a total of more than 800 short road test sections. Nearly 20 small bridge spans were crafted to examine everything from bracing techniques to pavement degradation. In all aspects, the AASHO engineers did their homework. 

The U.S. Army Transportation Corps carried out tests at the Ottawa Test Loop. Neighbors included miles of corn field and country roads. Photo Credit: Gerry Buehler

Ribbon Cutting Ceremony at Test Loop #6. October 15, 1958.

By October of 1958 the site was prepared and  the first traffic simulation occurred. Teams of Army drivers would circle the loops in heavy trucks and  trailers for hours on end to put the pavement through its paces. While the average Chevrolet weighed somewhere in the neighborhood of 3,500 pounds, a 1953 Mack Model B semi of the same era tipped the scales at 13,000 pounds...empty. You can see the value in running something more heavy duty if you're serious about testing its strength.

A truck leaves a turn-around and enters the straightaway at the Ottawa Test Loop.  Photo Credit: Gerry Buehler    

 

If you look at the map of the test site above, you'll  notice the army barracks on site. I'm sure working there had its high points, but to me, driving a 1950's semi truck in a circle all day in the middle of the Illinois countryside doesn't sound appealing. The value of their work was ultimately realized by the engineers and number crunchers in the main office. The data that was collected was indeed carried out during their 'experiments' behind the wheel. This laboratory was open until November of 1960, when the testing ceased and the AASHO compiled the data for publication and reference. 

Fuel Stop. Circa 1958

By 1962 the Ottawa test site had a new neighbor: Interstate 80. Life moved on and I'm sure by then there was a mountain of paperwork that was generated by years of study. All that's left of the site today is a short part of one of the loops and a brown point of interest sign on I-80 that most of us don't pay much attention to. In the end, what did this huge laboratory experiment yield?  It introduced the Generalized Forth Power Law, stating that a vehicle's damage to pavement was related to the 4th power of their axle weight. Or, in a nutshell, the tests gave engineers the proof they needed to make the following earth-shattering statement: 

Big trucks wreck roads quicker than small cars do.

And as more Americans wanted more and more goods and services delivered to them in the post-war boom years, the folks at the AASHO knew that more and more trucks would have to travel the interstates full of heavy trailers. Trailers crammed full of shiny Kelvinator refrigerators, Philco television sets and cases of Bubble Up cola. It wasn't just the big trucks that needed to go on a diet. The average weight of the American automobile was also creeping up toward 4500 pounds by the end of 1950's and there were more of them. More motorists and wider use of popular road network meant someone would have to eventually take care of it. This would eventually put a financial burden on the federal government to maintain the massive interstate system that was already under construction. Armed with the evidence, the AASHO clearly spelled out what causes the most damage to a highway and the best ways to counter that damage by sound construction and maintenance methods. Pretty neat stuff when you dive into the history of a simple road sign. If you pass it next time you're on I-80, give it a glance. That stretch of road near Ottawa, Illinois will never look the same to me again.


Epilogue, 5/2015 : I would like to extend a hearty thank-you to Gerry Buehler for sharing his service in the U.S. Army and for sharing his experience and photos from his time at the Ottawa Test Loop in 1960. (You can read his recollections in the comments section below.)

Its incredible history and we're grateful for your willingness to get in touch.

Cheers,

-D

*Photos in today's post were also courtesy of the Federal Highway Administration. They're good people.