Integration of life cycle assessment into planning and project delivery for pavements in the USA

摘要

Purpose Environmental impacts are typically considered in transportation decisions through planning and environmental review processes. Recent state-level legislation in the USA institutes requirements to track environmental performance of construction materials in bidding on public projects. To support this new initiative, this study aims to identify specific life cycle assessment (LCA) frameworks that can effectively impact the decisions on every level in the planning and project delivery process and evaluate the implementation readiness level. Methods The objective of this study was pursued through literature review and discussions facilitated at a workshop with representatives of six State Departments of Transportation (DOTs). Through the dialog with stakeholders, the details of the current planning and project delivery process were identified. After the participants were provided with background on LCA, LCA methodology, the most suitable to impact decisions at every decision-making level, was investigated considering key decisions (Why?), type of the analysis (How?), available data (What?), and the involved decision-makers (Who?) pertinent to each phase. The potential to develop tools to inform the decisions, the readiness level, and obstacles to LCA implementation was evaluated subsequently by authors and informed by a literature review. Results and discussion A consequential LCA was identified as the effective method to inform long-range planning. Attributional LCAs for a network and project level were regarded as suitable in programming and project development, respectively. Environmental product declatations (EPDs) were found applicable in bidding, while the construction phase was found best suited for data collection that can feed back into the upstream decision-making phases. The lack of a feedback loop between the quantified environmental impacts and the decision-making was identified as a major obstacle by stakeholders. A lack of clarity on progress toward environmental goals was specified as another hindrance. The development of tools and systems for communication and data transfer among the key stakeholders is expected to facilitate LCA use, close a feedback loop, and provide for progress tracking. Conclusions The relatively high readiness level of LCA implementation was identified in the pavement design phase (parallel to life cycle cost analysis (LCCA)) and in the construction phase (as-built environmental impact tracking and data collection). Initiating data collection in these two phases can provide an impetus for improving environmental performance and meaningfully inform other decision-making phases. Additionally, the importance of education and cross-collaboration is recognized by all stakeholders.