Plastic Roads in Netherlands Offer View of Future
By Aaron Crowe
The advantages of plastic roads almost sound like a utopian view of the future, if not Disney World’s Epcot Center: Virtually maintenance free, made entirely of recycled material, and no potholes.
Epcot, the Disney theme park where the future is forecast, doesn’t have roads made of recycled plastic, but a city in the Netherlands soon will. “Soon,” as in within two years in a pilot project in Rotterdam by the Dutch firms VolkerWessels.
Called “PlasticRoad” by its makers, the lightweight design offers numerous advantages compared to conventional roads such as asphalt and concrete:
- Recycling more plastic. The idea is to make PlasticRoad from plastic that usually gets incinerated. At the end of its lifespan, PlasticRoad is expected to be able to be recycled again for a new PlasticRoad.
- Recycled bottles and other plastics are used to make the prefabricated road parts that can be installed in one piece, making construction of PlasticRoad easier and installation simpler.
- Virtually maintenance free. Corrosion and weather doesn’t affect it, according to VolkerWessels. The road can withstand temperatures from below 40 degrees Fahrenheit to 176 degrees. It’s also much more resistant to chemical corrosion.
- Longer lifespan. Predicted lifespan of the roads will be tripled, according to the company. That leads to less road maintenance and less traffic jams and detours for such work. A 50-year lifespan is expected.
- Space underneath. PlasticRoad is hollow and installed on sand, leaving room under it for cables, pipes and water. Traffic loop sensors, measuring equipment and connections for light poles could be installed under the road.
Plenty of plastic
The company plans to use plastic from the oceans and to collect plastic waste at incineration plants in Germany and the Netherlands.
There seems to be no limit to the amount of plastic available for PlasticRoad. Nearly 269,000 tons of plastic pollution may be floating in the world’s oceans. More than 55 percent of all plastic waste is still being incinerated, according to VolkerWessels.
“There is more than enough plastic for the construction of PlasticRoads,” they say.
The idea was conceived by looking at the problems that municipalities and contractors deal with. These include waste, alternative materials for roads, and the future shortage of oil, which provides an important component of asphalt.
There are some potential problems with PlasticRoad, according to its manufacturers. But because the pilot project is just starting, the extent of some of these is still unknown:
Noise. Like asphalt, a plastic road is expected to be quiet. Minimal noise pollution is easier with plastic than asphalt, according to PlasticRoad’s makers. Fears that a plastic road would act as a large resonance box for sound need to be investigated more, they say. If more noise is caused on a plastic road, that sound energy could be used to generate power, they say.
Slippery in winter. Work is being done to see if the plastic can be made skid resistant when wet. If that isn’t possible, sand or crushed stone could be applied to the surface by pressing or printing, providing the required roughness.
Releasing microscopic plastic. The company is investigating if friction and wear on the road will release microscopic plastic particles that are dangerous for people to breathe and for the environment. A wear layer or special coating should prevent this, they say. Research is being done to determine how durable the material is.
Toxic in fire. A fire retardant or fire resistant coating can be used to prevent PlasticRoad from becoming toxic in a fire. Research is still being done.
Effect of prolonged sun exposure. The civil engineering sector already produces and uses several products made from recycled plastic that have no problems with prolonged exposure to sun or UV-light, the manufacturers say. Examples include timbering, scaffolding, sheet piling, bridges and light poles made of plastic material.
Water in seams. Just as existing roads have seams where water can enter and damage a road, the seams of PlasticRoad are being studied for optimal design. Connecting the prefabricated parts will leave seams, and the firm is working on minimizing the effects. One potential risk, for example, is that the lightweight roads will float if groundwater levels are too high.
Replacing asphalt roads
If PlasticRoad is to be successful in the United States, it’s going to have to replace or supplement asphalt, which is used in a majority of U.S. roads.
Asphalt can last indefinitely and needs occasional maintenance, says T. Carter Ross, vice president of communications for the National Asphalt Pavement Association, or NAPA. Asphalt is recycled at a 99 percent rate to make new roads, Ross says. Recyclable materials such as roofing shingles, blast furnace slag and ground rubber from tires are used to make asphalt, he says.
Asphalt is 99 percent aggregate, he says, such as from stone, rock and sand. A petroleum product that’s the heaviest part of oil is used as the glue in asphalt.
A major benefit of asphalt is that it’s a smooth, fairly continuous surface that doesn’t have joints or cracks like concrete, Ross says.
“It’s a flexible pavement” that is quiet, smooth and creates 4.5 percent better fuel economy than a rough surface, he says.
Asphalt also has drawbacks. It’s malleable and moves, especially when heavy vehicles stop. A bus stop, for example, can have “mounding where the bus always stops,” says Keith Platte, an engineering expert at the American Association of State Highway and Transportation Officials, or AASHTO.
If that mounding will occur on plastic roads is a question to be answered, Platte says.
“The concept of plastic roads seems like a good one,” he says, but the devil’s in the details. Those details include how plastic roads will take repeated stops from heavy vehicles, how they hold up to snow plows, and rideability, he says.
Asphalt roads have been tested for years and have a sense of reliability and low risk of material failing that isn’t there yet for plastic roads, Platte says.
“How much of a risk are they willing to take on to put these out in full force?” he asks.
Concrete pavement has been around since 1892. Most concrete roads have a design life of 20 years, though some last 30-40 years, compared to about 20-25 years that’s common for asphalt.
A drawback of concrete roads is that with the ground constantly being shaken by traffic, concrete can crack and extreme heat can cause expansion and contraction of a popout of the road, says Bill Davenport, vice president of communications for the American Concrete Pavement Association, or ACPA.
Normally colored white, concrete roads are made of cement, rock, sand and water, and other materials can be added, Davenport says. Strength and durability are its popular points.
“Concrete in itself is recyclable,” Davenport says. Old concrete can be crushed and recycled, sometimes on site during road construction, he says.
There’s also a product called roller compacted concrete, which is a drier mix of concrete that’s compacted by vibratory rollers and is typically constructed without joints. It’s considered fast and economical to install.
Davenport says he’s seen many road alternatives come and go. The testing of plastic roads is just beginning, he says, and lacks data and research.
“We are always open to learning about new technology, embracing new technologies if they have merit,” he says.
Why innovation in Europe?
Why plastic roads are being tested first in Europe instead of the U.S. is open for debate. It may be because Europe has a higher tax rate and less distrust of government, Platte says, which may lead to the government being more willing to take on such risks.
U.S. taxpayers may be more resistant to paying for such unproven roads. More than 90 percent of U.S. roads are built with public money or as public-private ventures, Davenport says, on a low-bid process. That mechanism for building roads may not be inductive to building roads that may have a higher upfront cost or aren’t proven to work well.
Or, like working less and paternity leave, Europe may simply be thinking ahead more and naturally considering recyclable road construction.