Abstract

Pavement Life-cycle Assessment Tool for Environmental and Economic Effects (PaLATE) is one of four pavement construction LCA models and the only belonging to the United States. Serving as a user guide to PaLATE (chapter 2), this document also develops an exercise/case study (chapter 3) that illustrates the utility of the tool and can act as a coursework supplement. Contexts are drawn for the tool (chapter 4) as they relate to pavement construction LCA models and sustainability, recycling, environment, and economics in the transportation community.

PaLATE performs environmental analysis according to the life-cycle assessment (LCA) methodology and economic analysis according to the life-cycle cost analysis (LCCA) methodology for highway pavement construction projects at the project level. As an LCA tool, PaLATE exhibits integrated, hybrid, streamlined qualities. PaLATE, like other LCA road construction models, can be utilized as part of the decision-making tool box to meet demands for more sustainable investments in transportation infrastructure. At the same, each of these tools exists in the research phase. Perspectives supported by tool analysis relate to the diversity of relevant stakeholders that include civil and highway engineers, transportation planners, politicians, material scientists, material manufacturers, environmentalists, recycling experts, and academics. Implemented in Microsoft ^® Excel, users can vary their analysis for a pavement section to account for a number of primary and secondary pavement construction materials and related processes; pavement construction processes evaluated independent of material type, generally common between highway pavement projects; the initial construction and/or maintenance pavement life-cycle stages; pavement construction material/process life-cycle stages; pavement structure layer; and the "calculation components" utilized, where calculation components is a term specific to this thesis.

Lacking an adequate user guide at this stage in its research development, PaLATE is incomprehensible. This document breaks PaLATE into calculation components that make the tool transparent. Calculation components are combined by the tool in a number of ways to execute calculations. Component categories include: user inputs (i.e. material volumes, etc.), user selections (i.e. transport mode, equipment models, etc.), default data housed in PaLATE from a number of sources (i.e. EPA emission factors, material densities, equipment, etc.), embedded calculations drawing on a number of analytical methodologies (i.e. EIO-LCA, equipment productivity, engine capacity, fuel consumption, etc.), and outputs (i.e. environmental–emissions, ground contamination, human health, etc., economic–net present value, annualized cost, etc.). The combination of calculation components for each disaggregate calculation are documented in tables. The Microsoft^® Excel worksheets connected to each calculation component are cited in the calculation component combination tables such that users "see" tool connectivity and know the location of assumptions, limitations, and more information related to each calculation component. The user guide portion of the document also features a number of flow charts related to LCA oriented boundary definitions, PaLATE disaggregate calculations, their distribution over material production, material transport, processes, and disposal material/process life-cycle stages, connectivity of user inputs to outputs, etc. Included is a completed exercise which serves several functions. Indirectly, this chapter acts as a case study which compares the use of recycled asphalt pavement (RAP) and virgin materials in a new asphalt pavement section, where outputs demonstrate PaLATE's utility. Throughout, the necessary user thought processes are documented for prospective users, demonstrating how to use PaLATE and the user guide portions of this document. Academics are encouraged to use the material as a course supplement. Finally, progress reports and discussions for the future relate to LCA road construction models and concepts incorporated in PaLATE such as economics and LCCA, environment, recycling, and sustainability as they relate to the domestic and international transportation communities.