Climate impacts and contribution of different transport modes

The transport sector produces about one fifth of the global CO, emissions and shows high growth dynamics. In the EU 28, the emission share of transport is 24.3% (European Commission, 2016, in terms of CO,._(]); the shares of modal contributions are 72% for road, 14% for navigation (including maritime), 13% for air and less than 1% for rail (values for 2016; see European Commission, 2018). Climate change impacts are a part of the external costs of transport, i.e. costs that are not covered by the producers and would have to be internalized through public interventions to create fair market conditions for the transport modes. In this section we first analyze the specific CO, emissions of the different transport modes, and secondly place them into the framework of external costs.

A study of the climate efficiency of different transport modes has to be related to the emissions per unit of traffic activity, e.g. per passenger kilometres (pkm). However, the transport modes compete only on particular distance bands, i.e. car/HSR on shorter and HSR/air on medium distances. Therefore, such comparisons require specifying a number of conditions:

Distance of travel: For air transport the emissions in the landing/take-off cycles are dominant on short distances; consequently, the comparative CO, advantage of land-borne modes decreases with distance.

Type of vehicles: Aircraft use is optimized according to distance and traffic volume of origin-destination (OD) pairs. In the case of HSR, there can be a number of stations in a corridor which provide sufficient patronage and determine the assignment of capacity (single or double train sets, one or double deck carriage, frequency of service).

Occupancy of vehicles: In aviation the load factors are between 75% and 85% for financially viable services. For HSR this depends on the service strategy. In the case of fixed service schedules (e.g. hourly), the average occupancy is low, as for instance in Germany where less than 50% are recorded. If the frequency is adjusted to the peaks of travel demand, as for instance in France, Japan or China, the occupancy rates are 70% or even higher, e.g. in Japan and China on the main corridors.

Activity dependent or total emissions: Most economic studies on external costs of transport are focusing on the travel dependent (“marginal”) costs (see e.g. European Commission, 2014b). In these approaches the emissions caused by the provision of infrastructure and vehicles are neglected. However, a fair comparison of climate efficiency of different transport modes requires considering the total emissions.

Weighing of emissions: In most publications on climate impacts, the emissions of aircraft flying at high altitudes are weighed by a factor of 2. According to IPCC (2015), this factor can be estimated between 2 and 5, although there is no clear scientific evidence. This is argued to be because of the higher impacts on radiation, e.g. through contrails and synergetic reactions of exhaust products in high altitudes (see Grewe in this volume).

The railway organizations offer CO, and other emission calculators which show the advantage of rail on medium distances. The example in Table 10.1 is taken from the UIC calculator.

It is obvious that the percent advantage of rail declines with increasing distance. However, it has to be taken into account that the rail traveller needs about 47 hours on the route from Lisbon to Stockholm and has to change trains ten times such that only a few railway enthusiasts will take this alternative into account. Using the CO, calculator developed by the I FEU Institute (2019) — based on theTREMOD model (2016) - the relative advantages of HSR come out almost constant (a factor of 6) for distances up to 1,250 km (seeTable 10.2).

This means that, depending on the essential assumptions, the operational climate advantage of rail on short flight distances compared with air is between

Table 10.1 Results from UIC emission calculator

Source: UIC.www.ecopassenger.org

Table 10.2 CO,_c emissions³ (in kg) dependent on distance

Source: IFEU (2016).

Basis: Well-to-wheel consumption of CO,_e, without emissions stemming from vehicle production/ maintenance and infrastructure provision. Average mix of energy production for rail.

the factors of 4 and 6 in Europe. In Japan the CO, advantage for Shinkansen trains vs. short-distance air transport can be much larger, up to a factor of 10, on very busy corridors (e.g.Tokyo—Osaka). A life-cycle comparison shows that the share of infrastructure provision to CO, production is much higher for rail compared with air (1.6 vs. 0.07 g/pass.-km or 11% vs. 0.06% of specific CO, production).⁴ The break-even point is calculated at 4,000 passengers per day⁵ while the actual patronage on the Tokyo-Osaka link is about 230,000 passengers per day (Hayashi et al., 2014).

It is noteworthy that for the existing Tokaido line, which became operational in 1964, the very low break-even point of 4,000 passengers per day is due to the low number of bridges and tunnels along this line.The planned new MAGLEV line between Tokyo, Nagoya and Osaka will cross the mountainous area of central Honshu and includes many expensive engineering structures such that the CO, production of infrastructure provision will be much higher. The environmental advantage of a MAGLEV connection - providing a maximum speed of about 500 km/h - vs. aviation is reduced to an estimated factor of 3, even under optimistic assumptions for patronage and energy efficiency of the system (see Hayashi et al., 2014).