In 2001, Indiana used shredded scrap tires beneath State Road 31; after a year of monitoring, the unusual road fill showed low settlement and minimal internal heating

In the summer of 2001 in Lakeville, Indiana, a group of construction workers did something that would have been laughed at a decade before: they buried thousands of shredded car tires under a highway. More precisely, researchers combined shredded tire material with sand in an equal, 50/50 mixture by volume, and used that blend as embankment fill on U.S. 31.

According to a 2006 study titled “Construction of a Test Embankment Using a Sand-Tire Shred Mixture as Fill Material,” published in the journal Waste Management, engineers monitored the road for roughly 200 days to see if it would subside, crack, or even worse, catch fire. None of these issues occurred. This is more important than you might think for a country currently stuck with hundreds of millions of old tires.

The problem hiding in America’s garages and junkyards


Tires are a unique problem for Americans. According to EPA’s 2026 Federal Register proposal on scrap tire recycling, the U.S. generated roughly 264 million end-of-life tires in 2023 alone. That’s a separate figure from the abandoned stockpiles left over from the “tire mountain” crisis of the 1990s, when piles nationwide held more than a billion discarded tires. Decades of cleanup have brought that legacy stockpile down to around 48 million tires still sitting in piles today, according to the same EPA proposal. Not only do tire mountains look unappealing, but they create mosquito breeding grounds and can cause slow-burning fires that can cause oil to run off into the soil and groundwater. The easiest option was to either bury or burn.

Why Indiana decided to pave over the problem

Purdue University researchers worked with the Indiana Department of Transportation to see if they could use shredded tires as fill for embankments instead of sand and gravel. This solved two problems in one. Lakeville became their test site. As rubber is a quarter of the weight of soil, it was an attractive option to build up low, soft ground without too much extra weight. However, there was a risk: earlier projects that used pure, undiluted tire fill had caused internal overheating from slow oxidation. That’s why the Indiana team diluted the tire shreds with sand rather than using them alone, and the road was fitted with sensors, settlement plates, and groundwater monitoring.

What the data actually showed

After a year of traffic, the results were quietly unremarkable, which, in engineering, is close to the highest compliment a project can get. The embankment subsided around 12 to 13mm (about half an inch) within the first several months and then leveled off. There was minimal internal heating and only trace amounts of increased manganese in the groundwater. The road functioned normally.

Some may wonder if this was just luck. But Indiana’s results weren’t an isolated case. A separate paper, “Prototype Tire-Shred Embankment Construction” by Todd Dickson, Donald Dwyer, and Dana Humphrey, was also published in 2001, in the Transportation Research Record. It documented a similarly timed pilot project by the New York State Department of Transportation, which built a 200-meter embankment core almost entirely out of tire shreds rather than a sand blend. That project, too, reported settlement within expected ranges and no internal heating. Two different states, two different research teams, two somewhat different mixtures, and both concluded that shredded tires, used carefully, can work as a construction material.

Why it’s not widely used

And yet, more than two decades later, shredded-tire fill still hasn’t caught on widely. Part of the explanation is traceable to EPA’s own 2026 proposal, which notes that regulatory and market barriers have slowed scrap-tire recycling broadly, even where viable uses already exist. Industry observers also point to inconsistent state-by-state rules for processed tire material, contractors’ preference for materials they already know how to handle, and a lack of strong national incentives for recycled fill. That second set of reasons is harder to pin to a single source, so it’s worth treating as a plausible explanation rather than a settled one. Indiana proved the idea works from an engineering perspective; nobody has fully proven it from a policy one.

Lakeville’s quiet embankment experiment, buried beneath an active, heavily traveled stretch of U.S. 31, is a reminder, for a generation worried about both climate change and aging infrastructure, that good ideas don’t always fail because they don’t work. Sometimes they fail simply because almost nobody outside a research paper ever hears about them.