Making Road Construction More Environmentally Friendly

Let’s face it, there’s nothing really sustainable about the current transportation sector in this country. While bike sharing programs and walkable, carless cities have emerged both domestically and abroad, the reliance on infrastructure – namely roads and rails, not to mention air travel – alone comes at a great cost to both the pocket book and the earth’s equilibrium. The extraction of metals to build planes, trains, and automobiles, as well as the coal, oil, and natural gas used to power these behemoths constitute an unsustainable system.

Some individuals and companies have devised options to make travel and roads in particular more “green.” Solar Roadways represents one such option. While replacing concrete and asphalt with electricity generating panels sounds like a wonderful idea, it may not quite be ready for reality. Another option suggests that manure may offer the best replacement for the current paving materials. Whether or not an alternative substance can be deployed remains to be seen. One positive move in the direction of making road construction more green is the development of standards, much like those that the United States Green Building Council created for homes, offices, and assorted structures.

However, all of these may be moot. A recent article from Derek Singleton suggests that contractors are the ones to blame for the inefficiencies and poor environmental conditions of roads. Singleton mentions that there is no life-cycle analysis of recycled materials, but more importantly, the “issue blocking green road construction [is] cost-plus contract pricing.” He describes cost-plus contract pricing as follows, “in the current road construction bidding structure, there’s a benefit for contractors using excess asphalt and man hours. Thus, there’s less incentive to explore greener methods of road construction.” Essentially, the more asphalt (which is derived from nonrenewable resources) used, the more the contractor gets paid and the less incentive to recycle asphalt.

According to Singleton, there are three “green alternatives” to using new materials: “hot in-place recycling“, “cold in-place recycling“, and “full-depth reclamation (FDR).”

The Asphalt Recycling and Reclaiming Association (ARRA) describes hot in-place recycling as an on-site, in-place method that rehabilitates deteriorated asphalt pavements and thereby minimizes the use of new materials. Singleton cites research out of British Columbia that supports the economic and environmental benefits of hot in-place recycling:

Of the three approaches to road recycling, the hot in-place method has the most research behind it. Hadi Dowlatabadi, an environmental scientist at the University of British Columbia, conducted an in-depth study of the hot in-place road recycling method as part of a carbon credits project. In analyzing the environmental and economic benefits, Dowlatabadi found that hot in-place recycling reduces material use by 80 percent and material transport by even more than 80 percent.

The article goes on to look at North Carolina, the only state that has scrapped the cost-plus contract pricing. As a result of this move, North Carolina has the highest rate of hot in-place recycling AND the lowest cost per square meter for road construction. Sounds like an economic and environmental win.

[Image source]