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Rainwater accumulates on impermeable surfaces, picking up vehicle oils and other pollutants as it flows away.
Peter Essick/Aurora/Getty ImagesThe origins of asphalt date back to 625 B.C., when it was utilized by a royal procession for road construction. In modern times, the U.S. boasts a national highway network spanning about 160,000 miles (257,495 kilometers) [source: U.S. DOT], not including local streets, roads, and parking areas.
Observe your street or parking lot during the next rainfall. Notice how water gathers near the edges and flows toward drains. In intense storms, you can witness and hear torrents of water surging into sewers, sweeping debris along. This phenomenon, known as runoff, exacerbates flooding, erosion, and water pollution.
Traditional pavement's inability to absorb water, due to its nonporous nature, leads to runoff. Green pavement, an innovative green building solution, is designed to be permeable, allowing rainwater to seep through and replenish the ground. This process prevents water, along with contaminants like oil and pesticides, from entering sewers. Dubbed green for its environmental benefits, many such pavements also incorporate recycled materials.
Is green pavement truly green in color? Not exactly. While most permeable pavements are gray or beige, certain companies have engineered durable grass turf capable of supporting even a helicopter landing pad [source: Netlon]. This eco-friendly pavement is a practical option for walkways, driveways, and parking areas, with the potential to transform highway infrastructure in the future.
What sets green pavement apart from traditional asphalt or concrete? Continue reading to discover the distinctions.
Are you a hands-on enthusiast with a passion for sustainability? With the right tools and expertise, you can construct your own green driveway for approximately $1,200. Start by leveling the area and setting up a drainage catch basin. Excavate a trench and layer it with crushed gravel. Purchase recycled plastic grass pavers and arrange them over the base. Fill the pavers with concrete sand, compact them thoroughly, and then lay sod on top, ensuring proper irrigation. Within weeks, you'll have a robust grassy surface capable of supporting your vehicle [source: HGTV].
Permeable Pavement
Plastic pavers typically include the components mentioned above.
MytourGreen pavement is an umbrella term for various eco-conscious paving solutions designed for specific environments, including hot climates, high-traffic zones, and low-use areas.
The term green pavement often refers to permeable pavement. Unlike conventional asphalt or concrete, permeable pavement is designed with pores that let water pass through, preventing pooling or runoff. Similar to a coffee filter, water seeps through the pavement into a layer of gravel, which naturally filters out pollutants. There are three main types of permeable pavements:
- Traditional asphalt/concrete -- This standard mixture excludes fine particles to enhance porosity.
- Plastic pavers -- These honeycomb-shaped plastic grids allow grass or vegetation to grow through their openings.
- Concrete pavers -- Concrete blocks spaced apart to improve drainage and water permeability.
When integrated into a comprehensive system, permeable pavement can remove the necessity for curb gutters and storm sewers [source: Green Resource Center]. It also reduces flooding risks by allowing rainwater to absorb into the ground.
Permeable pavement is versatile, commonly used for driveways, emergency lanes, parks, alleys, parking areas, and pedestrian or bike paths. While current green pavement lacks the strength for highways, advancements in materials may change this. Some porous asphalt highways are already operational in the U.S. and Europe [source: Georgia Asphalt Pavement Association].
Grass pavers, a type of plastic paver, are widely favored in landscaping and construction for their dual functionality as pavement and natural grass appearance. Various products like Grasspave2, Geoblock, Tuff Track, Grassy Paver, Grass-Cel, Checker Block, and Grasscrete are available, each with unique advantages and disadvantages [source: Invisible Structures Inc.]. These pavers enable grass growth even in high-traffic zones, featuring interlocking grid or honeycomb designs that support vegetation. The outcome is a durable grassy surface capable of bearing over 97,000 pounds (43,998 kilograms) per square foot [source: Grassy Pavers].
Next, we'll explore the advantages and disadvantages of green pavement.
Chicago's alleyways, designed to reduce main street congestion, are typically lined with garages and waste containers. These alleys often flood, straining the city's sewer system. In 2007, Chicago launched the Green Alley Initiative, retrofitting alleys with permeable pavement to mitigate flooding and promote groundwater recharge.
This pavement reflects heat, potentially lowering local temperatures. Chicago also promotes rainwater gardens and bioswales (plant-filled ditches) among homeowners to enhance water absorption and filtration [source: Green Alley Handbook].
The White Sox's U.S. Cellular Field features the nation's largest permeable pavement parking lot, marking a first for Major League sports facilities [source: Medill Reports].
Benefits of Green Pavement
Pavers allow water to permeate through to the ground below.
Maria Jauregui Ponte/Getty ImagesThe pavement and asphalt industry dates back to the 1800s. Belgian chemist Edmund J. DeSmedt introduced the first genuine asphalt pavement in the U.S. in 1870 in Newark, N.J. With innovations like automobiles and air travel, pavement has grown into one of the largest industries in the country [source: NAPA].
Traditional asphalt and concrete pavements come with drawbacks. Their nonporous nature prevents rainwater from seeping through, causing runoff. This runoff can carry pollutants like oil and gasoline into nearby streams and rivers, leading to landscape erosion.
Traditional asphalt also contributes to the urban heat island effect, making cities significantly warmer than surrounding areas. (Learn more in What is the urban heat island effect?) Green pavement offers solutions, including better stormwater management and environmental benefits.
- Green pavement often incorporates recycled materials. Unlike traditional concrete, which is energy-intensive to produce, many grass pavers are made from recycled plastic. When concrete is used, manufacturers can utilize byproducts like slag cement from iron production, reducing landfill waste [source: Green Highways Partnership].
- Permeable, light-colored pavement resists icing in winter because water doesn’t pool on its surface. Its design allows air circulation, keeping it warmer in freezing conditions and providing safer surfaces for walking and driving [source: Green Alley Handbook].
- In summer, permeable pavement stays cooler than traditional pavement due to its light color and air circulation. This "high albedo pavement" reflects heat, reducing surrounding temperatures and improving air quality [source: Green Alley Handbook].
Having explored the advantages of green pavement, let’s now examine its disadvantages.
The Leadership in Energy and Environmental Design (LEED) Green Building Rating System serves as the national standard for designing and constructing high-performance, eco-friendly buildings. An independent third party confirms that the building adheres to LEED standards, which encompass:
- Decreased operational expenses
- Minimized waste production
- Efficient use of energy and water
- Improved health and safety for occupants
- Lower greenhouse gas emissions
Buildings that meet these standards are awarded a LEED plaque. Additionally, LEED-certified buildings are eligible for tax rebates, zoning benefits, and various incentives, enhancing their value to builders. Incorporating green pavement into projects can earn builders LEED credits for managing stormwater, mitigating the heat island effect, promoting water-efficient landscaping, and using recycled materials [source: U.S. Green Building Council].
Challenges Associated with Green Pavement
Despite its potential, green pavement comes with notable challenges.
One major issue is the difficulty snowplows face with pavers. Unlike smooth surfaces, pavers often feature irregular shapes, such as plastic honeycombs or concrete blocks with gaps. This unevenness can cause plow blades to snag and damage the pavement. A potential solution is equipping plow blades with rollers, enabling them to glide over the uneven surfaces without causing harm.
The installation cost of porous or permeable pavement is higher compared to conventional pavement. However, advocates argue that the reduced need for drainage piping and other stormwater management infrastructure can balance out these additional expenses.
Permeable pavement is also susceptible to clogging, requiring unique maintenance compared to traditional pavement. Without proper upkeep, such as using industrial vacuums, sand and fine sediments can obstruct the gaps between pavers. To avoid this, the pavement must be vacuumed or pressure-washed at least twice annually. If used for public roads, governments would need specialized equipment and personnel to meet these maintenance needs. Winter sanding for ice can exacerbate clogging, leading to stormwater runoff and pollution, which defeats the purpose of the pavement [sources: Metropolitan Area Planning Council and Stormwater].
Additionally, porous pavement lacks the strength of traditional pavement. Continuous pressure, like heavy vehicle braking, can collapse its pores, leading to failure. As a result, it is not recommended for high-stress areas such as airport runways or highways with heavy truck traffic. Currently, it is best suited for flat or gently sloped areas where high-pressure braking is minimal [source: Government of Nashville]. However, stronger versions of permeable pavement are being developed.
The Green Highways Partnership (GHP) emerged from the Federal Highway Administration's (FHWA) initiative to make the U.S. highway system more environmentally friendly. Its mission is to combine transportation efficiency with ecological sustainability. Beyond porous pavements, the GHP advocates for the following enhancements to the current system:
- Bioretention swales, which utilize plants and soil to filter pollutants from stormwater runoff
- Preservation of forest buffers, which protect groundwater quality and provide food and habitat for wildlife
- Wetland restoration, which helps purify stormwater runoff
- Wildlife crossings, including bridges, tunnels, and barriers, to reduce collisions between vehicles and wildlife
- Soil amendments, a method of improving soil to better manage stormwater
- Use of recycled materials in highway construction, to lower energy consumption
Currently, the GHP operates in the mid-Atlantic states of Delaware, the District of Columbia, Maryland, Pennsylvania, Virginia, and West Virginia. The organization aims to expand the GHP into a nationwide certified program [source: GHP].
