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. Click on a characteristic below to learn more.
- 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.
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.
- U.S. Green Building Council (USGBC) LEED Certification
- FHWA Sustainable Highways
- ISI envision
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
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.
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 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.
Greenroads is a sustainability rating system for roadway design and construction projects. Originally developed and funded by Transnow at the University of Washington, WSDOT, Caltrans, TXDOT, MnDOT, ODOT, and Western Federal Lands Highway Division (WFLHD). Contact Transtec if you need help with Greenroads credits for your pavement project to meet these requirements.
- PR-5: Noise Mitigation Plan – Establish, implement, and maintain a formal Noise Mitigation Plan (NMP) during construction for the prime contractor.
- PR-9: Pavement Management System – Have asset management systems in effect that include the pavement and critical structural features on a project, such as bridges.
- MR-4: Recycled Materials – Use recycled materials as a substitute for virgin materials.
- PT-2: Permeable Pavement – Use a permeable (porous) pavement or pavers to control and treat at least 50% of the 90th percentile average annual rainfall event post-construction runoff volume to 25 mg/L concentration of total suspended solids (TSS) or less.
- PT-4: Cool Pavement – Use a pavement surface with a minimum albedo of 0.3 (measured using ASTM E 903) for a minimum of 50% of the total project pavement surfacing by area.
- PT-5: Quiet Pavement – Design at least 75% of the regularly trafficked lanes of pavement where the speed limit meets or exceeds 30 miles per hour (mph) with a surface course that produces tire-pavement noise levels at or below target levels. Test the pavements according to the on board sound intensity (OBSI) method described by the current version of AASHTO TP 76.
U.S. Green Building Council (USGBC) LEED Certification
LEED (Leadership in Energy and Environmental Design) is a green building certification system. Mainly, the system covers building design and construction however, hardscape including paved parking lots is included. Contact Transtec if you need help with LEEDS credits for your pavement project to meet the following requirements.
- Site Sustainability – Mitigation of the Heat Island Effect – At least 50% of the site hardscape (includes roads, sidewalks, courtyards, and parking lots) can be paving materials with a minimum initial solar reflectance index (SRI) of 29. This also applies to porous pavers (open-grid pavers) and open-graded (uniform-sized) aggregate materials. The solar reflectance index (SRI) shall be calculated in accordance with ASTM E1980 for medium-speed wind conditions. The SRI shall be based upon solar reflectance as measured in accordance with ASTM E1918 or ASTM C1549.
FHWA Sustainable Highways
Utilizes the self-evaluation tool, INVEST (Infrastructure Voluntary Evaluation Sustainability Tool), to integrate sustainability into transportation projects. Contact us if you need help for your pavement project to meet the following requirements.
- PD-28: Construction Noise Mitigation – Establish, implement, and maintain a formal Noise Mitigation Plan (NMP) during construction for the prime contractor.
Certification program for New York State Department of Transportation (NYSDOT) for sustainable transportation infrastructure.
- E-5e Diamond grinding of existing Portland Cement Concrete (PCC) pavement.
- S-2h Material selection & detailing that reduces overall urban “heat island” effect.
- W-2c Inclusion of “permeable pavement”
Illinois Department of Transportation’s (IDOT) sustainability performance rating system. Contact us if you need help with credits for your pavement project to meet the following requirements.
- D-2f Reduce urban “heat island” effect.
- E-3b Incorporate traffic system management techniques to reduce existing noise levels.
- E-3e Tining of pavement to reduce noise levels.
- W-1d Shoulders constructed of permeable pavement.
The Institute for Sustainable Infrastructure (ISI) is a partnership of the American Society of Civil Engineers (ASCE), American Council of Engineering Companies (ACEC), and the American Public Works Association (APWA). Envision is the associated sustainability rating system. Contact Transtec if you need help for your pavement project to meet these envision requirements.
- 3.2.1 Minimize Noise and Vibration – Carry out studies to predict the levels of airborne, ground-borne, and structure-borne noise and vibration, and propose mitigation plans to manage these to acceptable levels in the community.
- 8.1.5 Avoid Urban Heat Islands – Implement a design that avoids the creation of urban heat islands.
- References and Sources:
- CEEQUAL Assessment Manual for Projects Version 4, December 2008, Roger K. Venables, Section 11.3.
- LAWA Sustainable Airport Planning, Design and Construction Guidelines, v4.0, April 2009, PD4-LP-1
- ASTM, 2000. ASTM E1014-84: Standard Guide for Measurement of Outdoor A-Weighted Sound Levels.
- USDOT, 1996. Measurement of Highway-Related Noise, FHWA-PD-96-046 DOT-VNTSC-FHWA-96-5, May.