Waste tires accumulate quickly. An estimated one billion waste tires are generated around the world each year, while the United States generates approximately 240 million to 250 million annually, according to a 2026 review published in Transportation Infrastructure Geotechnology . The figures highlight the scale of a waste stream that can create storage, disposal, and fire-management challenges. Instead of sending some of those tires toward conventional disposal, engineers in Pennsylvania used processed tire material as part of a bridge construction project.
At the Tarrtown Bridge project on Tarrtown Road in Armstrong County, Pennsylvania, crews used tire-derived aggregate as lightweight fill in the bridge's two approach embankments. The aggregate consisted of processed, angular tire shreds, and the project used approximately 5,570 tons of the material, equivalent to roughly 557,000 tires. PennDOT monitored settlement and structural behaviour during and after construction, with the project demonstrating how the lightweight material could be used to address difficult ground conditions.
