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The Importance of Green Roads

Making our roads green matters, and it matters a lot. We may not realize it, but under that smooth, clean strip of asphalt we drive on -- and the layers of rock and soil further down -- lies an economic and environmental disaster that has been kept quiet for too long.

And yet, new technologies and new mindsets have begun evolving to help transform traditional blacktop. As the world turns its attention to addressing long overdue ecological and economic challenges, we have an unprecedented opportunity. Driving cleaner cars and commercial vehicles on dirty roads solves only a part of the problem -- get ready for green roads.

The Status Quo

The global roads network is vast and growing at one of the fastest paces in history. In 97 percent of the continental U.S., you're no more than three miles from a paved road of one kind or another, and the most recent CIA World Fact Book places the number of worldwide paved roads at 15.99 million kilometers. By comparison, the moon is a mere 384,400 kilometers (almost 239,000 miles) away. China's latest Five Year Plan calls for the building and renovation of 1.2 million kilometers (almost 746,000 miles), making good on its promise to build "a road to every village." Brazil, Russia, India and even Africa are not far behind, each with plans to massively invest in long-needed road infrastructures. The American Society of Civil Engineers says $186 billion is required to just improve the U.S. highways, and several thousand shovel ready projects are already benefiting from President Obama's stimulus package.

A new road can reduce the travel time and distance for transporting people and products and other material from place to place. However, for each mile of these new but traditionally constructed roads, thousands of tons of materials such as aggregate rock, concrete, asphalt and steel are needed, let alone all of the diesel fuel required to power the construction equipment. One mile of two-lane asphalt road with aggregate base can require up to 25,000 tons of aggregate rock (aggregates are the most mined resource in the world and are almost entirely non-renewable). In terms of greenhouse gas emissions, between the pavement and sub-base -- all the mining, transporting, heating, earthwork and paving work -- the average single lane-mile of freeway, will emit enough pollution to equal up to 1,200 tons of CO2. That's about the same as the total annual emissions of 210 passenger cars. In 2007, the U.S. alone laid down close to 37,000 lane-miles of new road.

The environmental effects of a road do not stop when construction is complete. The new road affects local plant and animal life as well as the region's water and soils. The road acts as a barrier that cuts through animal ranges and creates a crossing hazard, further diminishing wildlife habitats, especially if trees were cleared to make way for the road.

Increased travel through the area introduces invasive plant species to the existing vegetation. For as many as 1,000 meters [PDF] from the road, water and soils must contend with increased heavy-metal and salt deposits from gasoline and de-icing, as well as changes to run-off patterns and underground flow rates that affect larger bodies of water further downstream. In addition, the heat island effect that is generated does not just threaten creatures such as birds and snakes. Cool rainwater that lands on hot roadbeds is heated and then runs off into nearby aquatic ecosystems, where the rapid temperature changes can put fatal stress on life in the water.

And in populated areas, the general rise in atmospheric temperatures in the vicinity of the new road creates greater human demand for cooling, increasing emissions of carbon dioxide, sulfur dioxide and mercury.

While it is highly encouraging to see new efforts to green the transportation infrastructure (cleaner cars, light rail, urban mass transit), most of the world still goes to work each day on a road designed and built with yesterday's thinking.

Turning a Corner

So how can we reconcile the need for vastly improved and more extensive road infrastructure with the need to do so in a less damaging way? A number of efforts are beginning to generate interest in and momentum for what can be called green roads. Combined efforts by the EPA and Federal Highway Administration through support for the Green Highways Partnership, a standards setting program called Greenroads, and the Recycled Materials Resource Center, as well as efforts by the road building industry itself, has led to the beginnings of a new framework for green roads. Though acceptance, while growing, is still its infancy.

The Green Highways Partnership was born in 2002 when the Federal Highway Administration, in consultation with the EPA, named environmental stewardship and streamlining to be one its vital few goals. The GHP operates through a network of private and public partnerships to study and implement best management practices for concepts such as: watershed management; reuse and recycling programs for products that include coal fly ash, slag cement and old asphalt; and conservation and ecosystem protection such as wildlife crossings.
Building a green road with ECOroads materials.

Separate from the GHP work, EPA efforts include the new Tier 4 standards for non-road diesel engines, which are to reduce exhaust emissions by more than 90 percent and eventually reduce diesel fuel sulfur content from 3,000 PPM to 15 PPM. When fully applied, the agency says, "these reductions in NOx and PM emissions from non-road diesel engines will provide enormous public health benefits. The EPA estimates that by 2030, controlling these emissions would annually prevent 12,000 premature deaths, 8,900 hospitalizations, and one million work days lost." Both Cummins and Caterpillar have promised to meet these aggressive new standards.

Universities are also in on the effort.

The University of Washington, in a joint effort with the global civil engineering and construction firm CH2MHill, has created the Greenroads Sustainability Performance Metric for design and construction of new, reconstructed or rehabilitated roads. This system of credits is similar in nature to the LEED rating system designed for buildings. Through its seven categories of sustainable design features, credits are awarded based on dozens of initiatives, including storm water management, bicycle and pedestrian access, reduced fuel use and paving emissions, recycled content and pavement technology.

The University of New Hampshire-Durham, in cooperation with the University of Wisconsin-Madison and the Federal Highway Administration, has created the Recycled Materials Resource Center. For over a decade, their efforts have focused on developing guidelines for -- and promoting the use of -- recycled materials in transportation infrastructure construction and maintenance. Currently, about 94 percent [PowerPoint] of the 3.2 billion tons of aggregates used every year are virgin aggregate rock while 20 percent of all hot mix asphalt and Portland cement concrete end up clogging landfills.
Adding ECOroads to windrows and sub base.

The paving industry, too, is not blind to its environmental record. Both the cement and lime industries have spent years working on productivity and efficiency gains. In the United Kingdom, manufacturers exceeded their targets of improving specific energy consumption by 26.6 percent over 1990 levels ahead of schedule, recording a reduction level of 33.7 percent, the Mineral Products Association said in a recent article on AggregateResearch.com. Manufacturers in the lime sector achieved a specific energy consumption of 940kW h/tonne against a target of 955kW h/tonne, the article said.

In the U.S. and Canada, the cement industry reduced energy consumption by 37.5 percent from 1972 to 2006, according to the Portland Cement Association. In addition, the industry has formed the Cement Sustainability Initiative. The initiative, consisting of 18 of the world's major cement producers, promotes research into more efficient cement and has a created a framework of performance indicators for companies to keep track of their progress. The asphalt industry has also taken commendable steps to reduce its carbon footprint through the development of warm mix asphalt. This new asphalt requires substantially less heat and therefore consumes less energy and emits fewer greenhouse gasses.

Finally, a number of innovative and eco-friendly products are also beginning to emerge. Among the most promising are soil stabilizers and asphalt binders that provide the equivalent strength of aggregate base rock at a fraction of the cost and environmental impact. Many of these show promise in the green building space as well, proving that green roads innovations can provide benefits across the sustainability value chain. This could eventually lead to greener office buildings, residential developments, schools and the rest of the built environment.
Final shaping of the green road.

These innovators will have to contend with agencies and individuals wedded to the old way of doing things. The task is no easy matter, as these agencies can be burdened with bureaucratic inertia and bias toward existing industries and technologies. That said, several state departments of transportation are starting to recognize that the industry -- and overall approach to road building -- is due for a change, especially given an economy that is forcing most states and local governments to do more with less.

New York State Department of Transportation Commissioner Astrid C. Glynn said recently, "By encouraging sustainable transportation project designs, we are taking significant steps to conserve our natural resources, enhancing the quality of our lives and reaffirming our commitment to future generations."

While there is still a long way to go, when all these concepts are implemented, the complete product is a road that reduces toxic and greenhouse gas emissions, protects watersheds, reduces landfill use, protects ecosystems and preserves space for recreation. It is an engineering, economic and public policy achievement that proves that infrastructure construction and environmental preservation do not have to be a zero-sum game.

The Time is Now

There remains one other reason why green roads are so important and require a solution now, not tomorrow. In order to compete in the 21st Century, the developing world has to build out its own highway infrastructure, as we've discussed, to the tune of several million kilometers over the next 10 to 20 years. Builders and public works officials in Africa, India, China, Russia and all over Latin America have a choice: blacktop or green, dirty or clean.
Final compaction of the green road.

To use the same old construction methods would lead to unprecedented environmental impact and further contribution to global warming, all while incurring great economic costs to the budget. Now is the time for decision makers to embrace a new way to design, plan, build and maintain their road infrastructure, consistent with green road building practices, leveraging new technologies and know-how, and preparing their countries to take a leadership role in environmental stewardship and infrastructure development.

In the developing world, every single mile of road built is associated with a significant economic return, as reduction in travel times and costs improve all factors of life. Poverty can be reduced, as it was in Laos [PDF]. Access to healthcare improves, lessening risks to pregnant woman and children, as occurred in India [PDF]. School enrollment can increase as it did in Morocco. Income and employment opportunities rise as new businesses are created along the roads, and better access to financial services increases investment towards non-agricultural industry. Land values go up, further increasing access to capital and stimulating entrepreneurial investment. And, according to the Asian Development Bank, in China's [PDF] Shaanxi province "for every CNY10,000 invested in roads, 3.2 poor people are lifted out of poverty; and for every 1 percent increase in kilometers of road per capita, household consumption increases by 0.08 percent."

Of course all of this development does not just happen in the rural countryside. From Sao Paulo to Lagos to Delhi, by 2050 the world's cities will see their populations expand by 3.1 billion new residents. All that growth will bring with it a massive new demand for infrastructure. Green roads in conjunction with modern power grids, cleaner cars, large and dependable public transportation systems and sewage treatment facilities will help to greatly reduce the per capita carbon footprint of these thriving mega-urban regions.

As growth proceeds apace, it is also important to note that shifting a supply chain to another part of the globe merely moves the source of the smog to a new region. Instead of improving environmental impacts, the change can make things worse: A significant new part of the pollution over American soils now originates in China. That said, expanded infrastructure in the developing world will lead to significant improvements in supply-chain efficiencies of Western companies, leading to cost reductions and a smaller carbon footprint per unit of product -- a tangible benefit for companies, employees, and customers in the developed world.

The End of the Road as We Know It

The old ways are fading and new approaches to road construction are finally catching up with the times. A standard four-lane highway should not consume, over its lifetime, 2,600 barrels of oil worth of energy per kilometer. Just as the green building movement has finally reached the spotlight and gone mainstream, the green roads movement is not far behind.

By Omri Dahan and Alex Goykhman
Published August 26, 2009

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