Estimation of Carbon Footprints in Bituminous Road Construction: A Case Study

Carbon foot print is a term used to describe the total amount of carbon dioxide and other greenhouse gas (GHG) emissions for which an individual/process/organization/activity is responsible. The challenge of global climate change has motivated state transportation agencies involved in the construction and maintenance of transportation infrastructure to investigate strategies that replace the life cycle GHG emissions associated with the construction and rehabilitation of highway infrastructure. The road sector is coming under pressure to review current practice and the potential to reduce carbon emissions. To reduce GHG emissions, different approaches are adopted for road construction and maintenance, such as warm mix and cold mix technologies. Warm mix asphalt is produced at temperatures 20 to 40° lower than hot mix asphalt (HMA). Cold mix asphalt is produced and paved at ambient temperature using bitumen emulsion. The immediate benefit of producing and placing asphalt mixes at a lower temperature is the reduction in energy consumption, greenhouse gas emissions, fumes, and odors generated at the plant and the paving site. The life cycle approach has been accepted as a robust method of measuring carbon footprint. Tools and data sets have been developed to facilitate the measurement. Among them is the Calculator for Harmonised Assessment and Normalisation of Greenhouse Gas Emissions for Roads (CHANGER) developed by the International Road Federation (IRF). This paper outlines the common methodology of road carbon foot printing, the application of results in sustainable construction assessment schemes, and resources available to undertake such analysis. Case studies of using CHANGER are provided in India for different technologies. The CO₂ output of these projects is compared.