To establish a quantitative evaluation method of the global environmental load of the whole railway system, the environmental load of each element (railways and railway systems) as an aggregate of these elements was evaluated using the Life Cycle Assessment (LCA) technique. For vehicle running, which forms a large proportion of environmental load, the influence of each factor was also investigated.
The following shows an example of evaluation on the Tokaido Shinkansen. LCA was performed by classifying constituents into six categories (structures, track, trolley wire, signal/communication, stations, and vehicles,) and using a cumulative method to add all materials and resources from the stages of construction to operation (such as maintenance.) Vehicles account for 88% of the CO2 emissions by constituents, and operational energy accounts for 87% by life stage of infrastructure. In high transport density sections such as the Tokaido Shinkansen, CO2 emissions from vehicle running still form a large proportion, even when the infrastructure is included (Fig. 1). It was also shown that the results obtained by the cumulative method closely corresponded with those obtained by another method known as the input-output analysis method. An evaluation of factors affecting operational energy in vehicles accounting for a large proportion of the CO2 emissions was also carried out. From this, it was estimated that, for example, a 10% vehicle weight reduction in the 700-series Nozomi service between Tokyo and Osaka reduces CO2 emissions by 4.5%, and by 5.7% if aerodynamic drag is reduced by 10%.
The following shows an example in which yearly CO2 emissions are evaluated by transport criteria, using the input-output analysis method that estimates the amount of environmental load from transaction amounts between industries. The total amount of CO2 emission from road vehicles and trucks is much larger than that of railways. The ratio of running operation for the total amount of CO2 emission by road vehicles is large at about 70%, while that of railways is about 40%. The ratio of running operation is rather small because the national average of transportation density is much lower than the transport density of the Tokaido Shinkansen (Fig. 2). Amounts of CO2 emission by railways and buses per transported volume are relatively small, while those by road vehicles, trucks, and aircraft are large (Fig. 3). Based on these values, calculations of potential CO2 emission reductions through a shift from road vehicles and trucks to railways and buses show dramatic effects, even taking into account increases in CO2 emission due to infrastructure expansion. If, for example, a modal shift occurs in which 15% of transported volumes of road vehicles is shifted to railways and buses, 10% of aircraft to railways, and 10% of trucks to railways, a 7% reduction in CO2 emissions can be expected over the whole transportation sector.
As shown above, this technique can be used for the quantative evaluation of environmental load.