What is SPD?
SPD is a Windows-based decision-making software for evaluating the sustainability analysis of pavement design and products. It quantifies and compares the environmental and economic performance of pavement alternatives and results in the most sustainable pavement with an optimum balance between engineering, environmental, & economic performances. Pavement designers, transportation agency decision-makers, state highway agencies are the intended users of this tool.
How does it work?
The software defines the sustainability of pavement design based on a cradle-to-gate framework. An overall performance score which is the summation of environmental performance and economic performance represents the sustainability of pavement alternatives. The lower the score the more the sustainable pavement it is.
SPD measures the environmental performance of pavement alternatives by combining Environment Product Declaration (EPD) and Transportation Analysis. EPD is an LCA based tool defined by using predefined parameters based on ISO 14040. Economic performance is measured using initial cost which accounts for material cost, overhead cost, equipment cost, labor cost etc. of pavement construction. The two performance criteria, economic and environmental, are combined using the ASTM standard for Multi-Attribute Decision Analysis.
How is SPD different from other sustainability tools?
All the available sustainability measurement tools are based on Life Cycle Assessment (LCA) approach. The methodology, system boundaries, assumptions made during the data collection for LCA are not known to the decision makers using those data, due to which LCA cannot be applied for the comparison of different pavement alternatives. EPD, on the other side, are developed based on a set of standards and provides a reliable and comparable data.
Further, the collection of data for analysis of all pavement life cycle phases is time-consuming and tedious. Inventory data provided in EPD along with the inclusion of only cradle-to-gate framework alleviates the data collection burden for the pavement analysis. Due to these aspects of EPD, incorporating EPD into SPD creates a more reliable and easy comparison of multiple pavement designs.