Maine Once Buried 20,000 Tires Under A Road, But Here’s Why No One Does This Anymore

Back in 1992, the state of Maine shoved about 20,000 old tires price of rubber underneath a stretch of Dingley Road within the town of Richmond. It was an experiment to see if the state could mainly kill two birds with one stone: help roads hold as much as the freeze-thaw cycle that causes potholes, and cut down on rubber waste, too.

The freeze-thaw cycle is the phenomenon of water in the bottom wreaking havoc on roads when temperatures swing between seasons. We all know what you are picturing, though, and no, they didn’t just stack a bunch of tires in the bottom, Costco Tire Center-style, and pour gravel on it. Old tires were shredded into chips measuring 2 to three inches, then stacked right into a layer 6 to 12 inches thick, and only then did they pour about two feet of gravel on it.

Developed by University of Maine civil engineer Dana Humphrey, the scientific rationale behind this was that old tire rubber is comparatively light, a greater insulator than soil, and drains moisture well. Maine also had way an excessive amount of of it with nowhere good to go — in any case, tires expire even when they don’t seem to be physically worn out yet. 

And guess what? Within the short term, it looked as if it would work. When that first spring swung around, the 600-foot tire rubber-filled section had about half the frost penetration and was in significantly better shape than the regular gravel-only sections of that very same road, which were almost inconceivable to drive on. With this result, one other “rubber road,” finished with asphalt this time, was planned to be inbuilt North Yarmouth.

Fast-forward to 1996 and, in keeping with the Los Angeles Times, two highways that had been supported with old tires in Washington State began emitting smoke and a toxic gooey substance, posing an environmental threat to nearby marshes. And something similar had already happened to a tire-supported interstate in Colorado the autumn prior.

The underground rubber had heated as much as the purpose of cracking the pavement on top and giving off noxious smoke (and in a single stretch of Washington road, the odd flame) and a smell that reportedly resembled creosote and burnt plastic. The state Transportation Department said temperatures got as much as 160 degrees Fahrenheit on the surface, and deep interior temperatures were estimated around 450 degrees. A Coast Guard lieutenant said the substance was producing benzene, a known carcinogen.

Effectively, what happened was underground tire fires, and the rubber would have to be dug out, an operation that might require employees to wear protective masks and value $1 million to $3 million, per official estimates — and these are 1996 dollars. Adjusting for inflation, that is $2.1 million to $6.4 million in today’s money.

To underscore how potentially bad this was for the environment, experts said that every tire’s price of rubber down there contained a couple of gallon of oil’s price of hydrocarbon compounds. The Coast Guard lieutanant, a member of the service’s oil-spill strike team named Rob Myles, said, “We’re here because there’s potential for a million-gallon oil spill.”

Humphrey, the engineer who got here up with the experiment, theorized that the warmth was coming from steel belts still within the tire material rusting, or perhaps rubber compounds breaking down and creating sulfuric acid. Regardless of the cause, the chemical response stopped in Colorado when the highest layer of road was taken off.

For the record, that is different from the practice of grinding old tire rubber in making asphalt itself, which is a longtime road-building technique. Not only is that rubber not buried under a layer of something else, however it’s said to be handled and processed fastidiously. This makes for softer roads that, as you might have noticed when driving over them, provide quieter motoring. It also helps that they do not end in environmental disasters that cost thousands and thousands to repair.