Sustainability Trends Measured by the Greenroads Rating System

Greenroads, a system used to rate the sustainability of roadway projects, was used to evaluate 105 roadway and bridge projects in the United States for sustainable design and construction practices at various life cycle stages. A sustainability rating system can be a practical tool to help quantify and measure sustainability for a roadway project. The purpose of the investigation was to determine the state of the practice in sustainable roadway design and construction by application of Greenroads to a variety of actual projects. Forty projects identified as sustainable were compared with 65 typical projects representing conventional practice. The objectives of this study were to (a) identify trends in Greenroads project ratings, (b) benchmark the current state of the practice and identify potential areas for improved sustainability performance, (c) determine whether Greenroads can differentiate among projects on the basis of their sustainability efforts, and (d) identify the implications of these findings to practice. The results show that (a) some credits and categories are easily achieved, although achievement of others is more challenging and offers opportunities for improved environmental performance; (b) typical roadway projects tend to meet environmental regulatory standards but rarely do much more even when possible; therefore, they score fewer points for credits that focus on environmental benefits beyond the regulatory minimum; (c) contractors and materials suppliers appear to have unrealized opportunities to contribute; and (d) an early emphasis on the environment during project development appears to differentiate between typical and sustainable projects and manifest as higher Greenroads scores.