Sustainability Services
It is becoming more and more common that pavement construction must be green—it must meet sustainability and environmental requirements. Usually, we associate energy consumption, recycling, and life-cycle costs with sustainability. But, there are pavement surface characteristics that can be included in the sustainability calculations.
Surface Characteristics and Sustainability
The following pavement surface characteristics impact sustainability and may qualify for credits or points in various sustainability programs. Contact us if you need help understanding how to design, specify, or construct pavements with surface characteristics meeting sustainability requirements.
- Solar reflectance (albedo) – contributes to the urban heat island effect.
- Noise – environmental and social effects.
- Permeable pavement – affects stormwater runoff.
- Rolling resistance – affects energy consumption.
Solar Reflectance Index
Both the Greenroads and USGBC programs allow points or credits for pavements having SRI that meets a minimum threshold.
Solar reflectance index (or albedo) of a surface is a measure of the amount of solar radiation reflected by the surface relative to the incident radiation. SRI is an important quantity because of the urban heat island effect. Urban heat island is the name used to refer to the effect of urban areas becoming hotter than surrounding rural areas. The temperature difference can be up to 10 degrees.
The heat island effect is an environmental and sustainability concern because it increases summertime peak energy demand, air conditioning costs, air pollution, greenhouse gas emissions, heat related illness, and even mortality. Large surfaces, such as paved parking areas, may contribute to the heat island effect, depending on their SRI. Surfaces with high SRI contribute less than surfaces with low SRI.
Standards and test procedures related to solar reflectance and SRI:
- ASTM E 1918 – Standard Test Method for Measuring Solar Reflectance of Horizontal and Low-Sloped Surfaces in the Field
- ASTM C 1549 – Standard Test Method for Determination of Solar Reflectance Near Ambient Temperature Using a Portable Solar Reflectometer.
- ASHRAE Standard 189.1 – Standard for the Design of High-Performance, Green Buildings
Noise
Reduced traffic noise improves the environment and, in some cases, this can be achieved through reduced tire-pavement noise. The Greenroads program allows credits for pavements meeting maximum noise levels as measured using the OBSI method. Visit our Noise page for more information on quieter pavements and the OBSI method.
Permeable Pavement
Managing runoff through use of a permeable pavement contributes to sustainability by way of reducing erosion, water pollution, and improving habitat. Permeable pavement can also improve safety through reduced splash and spray, and improve the environment through reduces tire-pavement noise. See our Splash & Spray and Noise pages.
Rolling Resistance
Rolling resistance is the resistance to the motion of a tire rolling on a pavement, but not including resistance due to braking. Rolling resistance is caused by energy dissipating mechanisms such as the tire deflections that occur in the contact patch. These deflections are greatly influenced by the tire pressure, so tire pressure is a significant factor in rolling resistance. Reducing rolling resistance means energy savings. For an individual tire, the amount of energy saved may be very small. However, when multiplied by the number of tires in the nation’s vehicle fleet, and the number of miles traveled, a reduction in rolling resistance can translate to a very large overall energy savings.
There are at least three pavement surface characteristics that contribute to rolling resistance. Contact us if you need help researching, specifying, or measuring the effects of these pavement characteristics.
- Smoothness – Rougher roads cause more deflection of the tire and vehicle suspension which dissipates energy. Smoother roads can decrease rolling resistance and save energy.
- Surface texture – Texture in the micro and macro ranges affects tire and tread block deflections and can influence rolling resistance.
- Pavement stiffness – Compliant pavements deflect more under load. Stiffer roads can decrease rolling resistance and save energy.
Sustainability Programs
There are several programs contain requirements applicable to pavement surface characteristics. Here are a few. Click on the program to see more information. Contact us if the sustainability program for your project is not listed.
How can we help you with pavement sustainability?
Call us at +1 (512) 451 6233 or use the form to send us a message.