Development and Implementation of a Lifecycle Carbon Tool for Highway Maintenance

Abstract

The highway maintenance sector within the United Kingdom consumes considerable amounts of natural resources and accounts for a large amount of carbon emissions. Carbon emissions reduction is now considered an integral part of tender selection criteria and project performance issue by highway clients. This requires contractors to be able to assess and reduce both direct and indirect emissions associated with highway maintenance. This presents a challenge for the sector as despite the availability of methods to assess carbon there are no routine tools to allow a lifecycle assessment (LCA) approach to carbon reduction as part of ongoing maintenance management. Thus, there is a need for a consistent, project-focused carbon assessment tool, underpinned by a robust LCA methodology that can assess emissions and emissions reduction across core highway maintenance processes. This paper describes the development and business implementation of such a tool based on the Publicly Available Specification (PAS) 2050 protocol. The protocol is an independent standard developed by the British Standards Institution (BSI) in 2008 and updated in 2011 to produce a consistent approach for lifecycle emissions assessment from goods and services. It offers an iterative process, where the scope and objectives of the assessment are defined, relevant data collected for analysis and interpreted within the scope and system boundary defined by the standard. Twelve case studies were undertaken using the tool and the results demonstrated the tool’s potential to produce credible emissions information that can be integrated into highway maintenance decision-making processes. The tool identifies areas of emissions hotspots, opportunities for reduction, and then establishes a reduction hierarchy that can allow emissions reduction efforts to be prioritized in lifecycle terms. The study further presents sensitivity analyses with respect to choice of fuel, distance to site, material transport mode and distance, and design life of pavements. Although the implementation of the tool presented in this paper is specific to pavement resurfacing works, the tool can also be used to assess carbon emissions for other core highway maintenance processes, such as road marking, street lighting works and grass cutting, with the potential to evaluate full environmental impacts (e.g., Toxicity, Acidification and Ozone formation) associated with such highway maintenance processes.