We’ve all been there, driving through the city in a rush to get somewhere keeping our eyes on traffic, when our car suddenly hits a huge crater in the road and boom … our car bottoms out. The loud thud vibrates our core as we hope and pray that our vehicle has escaped the moon landing unscathed. It’s happened too many times recently for me to ignore. It even happened while I was running, luckily, my ankle ligaments have a similar flexibility to Gumby’s body. It was the last blow to my ankle (and pride), that pushed me to start thinking about the environmental impact of our roads. As a runner, I notice that most of our neighborhood roads in Dallas are composed of concrete, much harsher on your joints than asphalt. But, which is better for runoff pollution?
According to the Federal Highway Commission, there are a total of more than 4 million miles of road in the U.S., of which 2.6 million miles are paved. Most roads are paved with asphalt or an overlay of asphalt. Asphalt material is composed of 95 percent stone, sand, gravel and about 5 percent asphalt cement — a petroleum product (National Asphalt Pavement Association). Asphalt is favored for its cheap price, ease to construct and provides a smooth ride. Pavement sealant, the black tar looking substance, is used to seal and protect the asphalt. In two recent papers by the U.S. Geological Survey, this toxic pavement sealant has been found to damage DNA and impair DNA repair in aquatic life. When it rains, water runoff flows across roads picking up contaminants from the surface and carries the toxins to our water bodies. The asphalt has human health impacts as well. The National Institute for Occupational Safety and Health evaluated the research on asphalt and found known carcinogens in asphalt fumes generated at work sites.
Concrete has a higher albedo than asphalt — which means it reflects more solar energy, keeping it cooler and reduces heating of our atmosphere compared to the high absorption and heating of asphalt. More asphalt would actually mean a warmer city and an increase in our urban heat island effect. I guess I will sacrifice my joints for climate change – although the best thing to run on are dirt trails or the cushy material on the Katy Trail running path. Concrete is not without its environmental impacts, as the process to make concrete is the second largest emitter of greenhouse gases, only behind coal production.
Both materials are unfavorable for producing a sustainable road solution and both contribute to erosion by increasing runoff. But there are other creative options popping up around the world. The Netherlands have been investing in a “virtually maintenance free product” made from recycled plastic to create roads. The plastic roads can handle temperatures ranging from -40F to as high as 176F, and the company states the lifespan is three times as long as typical asphalt roads.
That’s promising! But, also a little worrisome — when exposed to solar radiation will the plastic leach toxic air pollutants into the atmosphere or leach toxins into our water supply? Can you drive safely on the road when wet? The idea is still in the testing phase, but I wouldn’t be surprised to see a prototype soon. The Netherlands is the same country that recently installed a 230 foot stretch of bike lane embedded with solar panels that created more energy than expected in its first six months. There are also a few companies within the U.S. providing alternative solutions to paving, such as a California-based company Natural Paving Solutions, who boast a lower environmental impact water-based solution.
Studies have shown deteriorated roads (ie: Dallas’ pothole-ridden roads) have a negative impact on fuel consumption, costing us more to travel on potholes and posing a greater impact on the environment. Creative solutions need to be explored to find a product that will provide us with safe roads to travel on with little impact on the environment. Or maybe we should invest in out-of-the-box forms of transportation that can creatively meet our travel needs without the strain on our environment. I’m ready for the creative future.