Comparative analysis of materials and energy between sustainable roadway rating systems

Abstract

A sustainable roadway rating system (SR2S) consists of a set of indicators to comprehensively measure the sustainability performance of roadway projects. The sustainability level of the systems can be improved by implementing appropriate strategies pertaining to materials and energy. In the peer-reviewed literature, some studies have conducted shallow comparisons of different SR2Ss and no studies have compared the significance of material and energy indicators in existing SR2Ss. To bridge this research gap, five existing SR2Ss were considered. These five SR2Ss described overlapping categories of indicators. Material and energy-related indicators (MEIs) were identified from the representative SR2Ss by conducting content analysis. Similar indicators were regrouped into six different material and energy-related features (MEFs), corresponding to six categories of indicators: local materials; long-life designs; materials obtained using the reduce, reuse, and recycle (3Rs) concept; energy efficiency; earthwork; and hazardous materials. Based on the relative significance index (RSI), the weightings of the selected SR2Ss and the significance of MEIs according to six MEFs were explored. In terms of the aforementioned criteria, the Illinois Livable and Sustainable Transportation gives the greatest weight to material and energy (34.7% of the total points), whereas GreenLITES gives the least weight to material and energy (i.e., 26.8% of total points). Regarding MEFs, SR2Ss focus more on materials obtained by using the 3Rs concept and energy efficiency. This means that indicators pertaining to these two features were considered to contribute significantly to evaluations of roadway sustainability. Aside from 3Rs and energy efficiency, hazardous materials were deemed to be not highly relevant to SR2Ss. Discussion on the indicator requirements related to material and energy are further provided based on different MEFs.