抄録
Objective. Road traffic contributes significantly to carbon dioxide (CO2) emissions. Road improvement projects are one of the effective measures to reduce CO2 emissions. In this study, a methodology based on the Life Cycle Assessment (LCA) approach is developed for evaluating environmental impacts of road improvement projects.
Results and Discussion. A framework for evaluating environmental loads from road transport system including road infrastructure and vehicle traveling is proposed. The framework also enables us to analyze changes in driving conditions that are influenced by road improvement. Further, it evaluates the impacts due to induced traffic and change in traffic speed. The method is applied to a road improvement projects involving removal of a railway crossing by constructing an elevated track. A project undertaken in this study can reduce System Life Cycle CO2 (SyLC-CO2) because it improves driving conditions by reducing stops and congestion due to railroad crossing. However, sensitivity analysis shows the following important findings: 1) SyLC-CO2 increases if traffic volume increases by more than 1.28 times after the project; 2) For a crossing where the traffic volume is less than 3,000 vehicles, such a project is unsuitable because the SyLC-CO2 increases after the project; 3) Large traffic volume is not required to reduce SyLC-CO2 if the crossing is closed long times.
Conclusions. The results of a sensitivity analysis carried out under different traffic conditions indicate that there is an overall decrease in CO2 emissions because, despite improvements in driving conditions, the environmental load contributed by road traffic is greater than the total load contributed by infrastructure construction and induced traffic.
