Abstract
Objective. “Uncertainty” generally exists when applying LCA to environmental load analysis of transport systems. Hence, there is a need for a systematic way of presenting the results by clarifying such uncertainties and avoiding any misleading interpretations. This paper provides a method that shows analytical results with their associated uncertainties.
Results and Discussion. This paper considers inventory analysis for an LRT system and investigates uncertainties in each stage. The uncertainties are organized into the following three groups: (1) Errors associated with emission factors, (2) errors from assumptions, and (3) errors from ripple effects. In discussing how to cope with these uncertainties, two important parameters affect results. One is the variance in embodied emission factors used for computation; the variance range for nine types of factors is analyzed. Another is a parameter related to assumptions and limitations of data and calculation (e.g., lifetime, transport demand, and congestion rate). Sensitivity analysis is utilized for representing uncertain factors and exploring methods of presenting eco-efficiency information. The total distance traveled, number of passengers, and travel speed serve as indicators of transport system performance. In this way, transport plans are not developed by simply evaluating the environmental aspects; different levels of demand are also considered to allow decision makers to determine an appropriate transport system. Consequently, a Type III environmental label is proposed to make environmental information available for public inspection.
Conclusions. This paper proposes an “Eco-Report” for transport systems, which specifically includes life cycle environmental load, sensitivity analysis, eco-efficiency, and other issues that require attention. This report represents the results of LCA together with the associated uncertainties; it will help policy makers understand environmental information.
