Rubber makes the roads
When Riverside, Calif., first tested rubberized asphalt in a pilot project in the mid-1980s, its intent was to help the environment, using recycled tires that would otherwise end up in landfills. But, after a few years, public works officials found that rubberized asphalt also could withstand heat and heavy trucks, and tended to crack less than conventional asphalt. Various studies also found that it reduces traffic noise by 4 to 6 decibels, mainly on streets with low levels of truck traffic. “Noise reduction is important, not only for commuters, but for nearby communities,” says Ibrahim Massoud, a senior engineer for Riverside’s Public Works Department.
In the last 20 years, Riverside has expanded its use of rubberized asphalt after determining that it is more durable and costs less to maintain than conventional asphalt. “Rubberized asphalt costs about $5 to $7 more per ton than standard asphalt, but we think it reduces our road maintenance costs by 10 to 12 percent because it lasts longer, so it’s a worthwhile investment,” Massoud says.
Riverside currently overlays about 20 miles of roadway each year — or roughly 90 percent of the city’s annual paving projects — using rubberized asphalt. All of the major paving work is outsourced to private firms, which make their own asphalt using recycled tires from a variety of sources.
About 1,600 scrap tires typically are used to overlay one lane mile of asphalt roadway, so multilane resurfacing projects can require thousands of recycled tires. For example, roughly 40,000 scrap tires were used to make 13,000 tons of rubberized asphalt for a heavily traveled 2.5-mile stretch of Alessandro Boulevard between Chicago Avenue and Trautwein Road in late 2006. During the past eight months, the Public Works Department resurfaced 10 miles of major, collector and residential streets, using approximately 16,000 tons of rubberized asphalt at a cost of $1.3 million.
Since 2004, the city has been receiving grants from the California Integrated Waste Management Board to help pay for rubberized asphalt projects. The grants reimburse the city $5 for each ton of rubber asphalt used.
Project: Rubberized asphalt road resurfacing project
Jurisdiction: Riverside, Calif.
Agency: Public Works Department
Date began: Latest road resurfacing project began in August 2007
Cost: $1.3 million