24 March 2021: In light of the Paris Agreement and the European Green Deal’s goal of reducing greenhouse gas emissions from transport by 90 per cent by 2050, the European Environmental Agency published a report on Train or Plane? in order to inform decision-makers on the current status and environmental impact of rail and air transport in Europe. Making a shift towards the most sustainable transport modes can contribute to the emissions reductions goal. The report identifies the shift from air to rail playing a key role.

The report analysed 20 city pairs within different distance bands throughout Europe and with varying degrees of rail connection quality. For each of these city pairs, an additional pair of alternative locations close to the main cities potentially served by the same rail station or airport is also analysed.

The report concluded that rail travel is always a sensible choice as air travel emission impacts are higher on a pax-kilometre basis. However, flying is not necessarily the most harmful choice when compared with road transport (assuming single occupancy in cars). In fact, travelling in a well-occupied diesel, petrol, or electric car (4 pax) has significantly lower emissions compared to air travel. However, the emissions of only one person travelling in a car are the highest among all modes, and a shift from car to rail would greatly contribute to emission reductions as high speed trains are found to be more environmentally friendly because of the high occupancy rate.

The report also acknowledges uncertainty on non-CO2 effects from aviation, which compared to high-speed trains causes more than six times higher emission costs. When it comes to noise, noise costs for rail are comparable or higher to the ones of air travel as they depend on distance whilst aviation’s depend on take-off and landing.

Based on the shares of emissions of each category, the report finds that for air travel the climate costs are the most

Important while for rail, the noise has the highest share.

However, it is important to note that a shift to rail requires new infrastructure, which can quickly result in net GHG emission reductions if the GHG intensity in the construction of the line is low (i.e. if it does not require many complex structures, such as tunnels and bridges), if there is a lot of traffic diverted from more GHG-intensive modes of transport and if the occupancy rate is consistently high. However, more attractive rail options may also lead to additional demand for transport. This could undo some of the environmental gains from switching to rail.

Improving the environmental performance of aviation remains highly important. The renewal of the fleet with modern aeroplanes and engines has already resulted in fuel efficiency gains. The regulatory limits for engine nitrogen oxide (NOx) emissions have been tightened over time and individual aircraft have become less noisy. The more widespread use of sustainable aviation fuel and improvements in ground operations and air traffic management could further reduce the negative environmental impacts of aviation.

The report also highlights lessons learnt. When it comes to modal shift, a question of high importance is: in which cases does flying offer irreplaceable benefits for travellers and under which conditions can it be replaced with less polluting modes? The report states that as short-haul flights have a disproportionate impact on health and the environment, efforts should focus on replacing those flights, which also usually offer the right travel distance  for which good, less polluting alternatives tend to be most readily available or are easiest to develop. The report also suggests that aviation and rail should be complementary given their advantages and disadvantages: aviation should focus on routes where an alternative is not, or not yet, present while working on a more integrated railway network in Europe and offer multimodal trips (air + rail trips). To do so, airports need to be connected by highspeed trains that are environmentally sound and also more affordable.

You can access the full report here [1].