Better Roads

July 2013

Better Roads Digital Magazine

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HighwayContractor The Upper Big Tujunga Canyon Road project, at 1.2 million square feet, is one of L.A. County's largest CIR projects to date. By Daniel C. Brown, Contributing Editor Photos courtesy of Pavement Recycling Systems. CIRL.A. a Hit in Cold asphalt recycling offers "a lot of positives" for L.A. County Department of Public Works O n seven projects performed in just the past two years, the Los Angeles County Department of Public Works has used cold asphalt recycling methods to save $3.15 million in rebuilding its asphalt streets, compared to the hot mix asphalt process. Cold asphalt recycling is a "taxpayer-friendly" and sustainable pavement rehabilitation solution. "I think cold recycling is an approach that agencies should really consider in maintaining their road network," says Greg Kelley, assistant deputy director for the L.A. County Department of Public Works. " It has a lot of positives including lower costs and reduced greenhouse gas emissions compared to hot mix. On our seven cold asphalt recycling projects we completed in the last year and a half, we calculated that we reduced the greenhouse gas emissions by 80 percent compared to hot mix treatments." Five of the seven projects were done with cold-in-place recycling (CIR), which uses mobile asphalt recycling trains that move down the road and recycle the material in place; two 6 projects were completed with cold central plant recycling (CCPR), which uses a stationary plant located in close proximity to the job site to recycle the asphalt. In the spring of 2012, L.A. County performed a threequarter-mile CIR project on Altadena Drive. Pavement Recycling Systems (PRS) was the subcontractor for the recycling portion of the project, and Hardy and Harper was the general contractor. "That was our first test with an urban setting," says Kelley. "We were a little bit concerned about what impacts the cooler springtime weather would have on the CIR treatment, but it performed very well." At Altadena Drive, the county first milled off 1.5 inches of asphalt and then performed a 3-inch CIR treatment on the remaining pavement. The top 1.5 inches was removed because the roadway had existing curb and gutter and the county wanted to keep the same grade, and add a 1.5-inch overlay at the end. The CIR process began with a Caterpillar PR 1000 milling machine. PRS milled and recycled Altadena Drive to a depth of 3 inches. The 1,200-horsepower mill July 2013 Better Roads HighwayCon_BR0713.indd 6 6/28/13 9:07 AM

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