Ripping up the road
Cold in-place recycling makes road work more sustainable.
Sunday, May 23, 2010 - 21:02
Photo: Austin Russie/Flickr
We all hate road construction. The traffic congestion, potential for accidents and detours all play havoc with our schedules and serve as an overall inconvenience. But every summer it comes back full force, haunting our highway drives and forcing us to slow down and appreciate the workers in orange vests who bring us safer roads.
Right now a team sits in front of my house, scraping old asphalt off the road and applying a new layer. I couldn't help but wonder what becomes of the discarded material and was delighted to find that the Illinois Department of Transportation (IDOT) has a green program cited by the EPA as a national model for road construction projects. IDOT uses a very cost effective and environmentally conscious process for repaving lower volume roads called cold in-place recycling (CIR).
One of the best aspects of CIR is its reuse of material at the construction site, usually performed by a line of machinery called a "train." In the past, grounding projects required a stock pile of broken up asphalt to be trucked off, much of it reaching landfills. CIR takes the top four inches off the road and pulverizes it in a milling machine. With a touch of oil and some binding additives, IDOT is able to rejuvenate almost 100 percent of the original substance without moving it from the work site. Not only does this save tons of rubble from clogging landfills, but also keeps the fuel and emissions for hauling it to a bare minimum.
What happens to material that doesn't quite make the grade and can't be reformed into pavement? IDOT turns it into shoulder aggregate.
Recycling the existing pavement performs a service for the environment in many ways. By reusing the pulverized asphalt, IDOT saves money for the state coffers by not purchasing new aggregate or suffering both the financial and environmental effects of transporting it to the work site. The process is called "cold" for a reason; by not heating the new asphalt, very little pollution is generated. Say goodbye to the noxious fumes of yesterday's road construction!
IDOT continues its recycling efforts throughout the department, from office supplies, oil, anti-freeze and approximately 50,000 aluminum road signs each year. According to its website, this program saves 190,000 gallons of water, 427,000 pounds of aluminum and $600,000 annually. The old tires and scraps of rubber littering the roadways — 1,000 tons of them! — are gathered and sold for reuse in playground equipment, among other things.
The fun doesn't stop with recycling. IDOT promotes sustainability via new vehicle purchases of hybrids and trucks that use biodiesel. They have refitted existing vehicles with emission control devices and established a limit to the time trucks can be left idling. Best of all, for every tree removed during road work, a new one is planted.