A Methodology for Identifying Lower Carbon Transport Systems for Inter-regional Passengers: Rail vs Aviation

The carbon dioxide (CO2) emissions reduction policies for the inter-regional passenger transport system highlight on the two factors: 1) the aviation sector is the slowest to eliminate use of carbon fuels; and 2) aviation is expected to contribute more to greenhouse gas emissions than other transport modes. A methodology for identifying an inter-regional transport system with lower CO2 emissions is proposed. This study aims to explore the possible changes in Life Cycle CO2 (LC-CO2) per passenger-km and ecoefficiency indicator including considering travel speed as a result of a shift from aviation to the high speed railway system (Shinkansen). CO2 emissions both for Shinkansen and aviation are estimated by applying the Life Cycle Assessment (LCA) method and taking into account of dominant parameters such as passenger demand. CO2 exhausted from aviation and Shinkansen during operation and the additional LCCO2 from providing new infrastructure are estimated. First the sensitivity with the number of passengers for a 500km long corridor is analyzed. The main results are as follows: 1) CO2 per passenger-km from aviation hardly vary with the number of passengers; 2) LC-CO2 per passenger-km for Shinkansen is inversely proportional to the number of passengers; 3) LCCO2 per passenger-km for Shinkansen is lower than that for aviation for the passenger volume of approximately 1,200 or more passengers per day; and 4) for eco-efficiency, the break-even point is more than around 2,000 passengers per day. The second considers the distance and travel demand for both aviation and Shinkansen. A possible shift from the current demand for aviation to Shinkansen is compared for each inter-prefectural OriginDestination (OD) pair. It is found that Shinkansen is more advantageous for OD pairs with higher demand and shorter distance. An application to the inter-prefectural ODs in Japan shows the conditions that provide an advantage of lower CO2 emission for Shinkansen or aviation.