Urgent action is needed to curb climate change and reduce transport emissions, and the aviation industry recognises the need to ‘go green’ and achieve carbon neutrality by 2050, as per the ambitious goals of the European Green Deal.

EUROCONTROL Think Paper

In parallel, many commentators have hypothesised that some air routes should rather be operated by high-speed trains or sleeper trains. This Think Paper aims to assess the practicality of an increased shift to rail, and the environmental, economic and societal implications that this would have as part of a wider green, smart and affordable mobility approach.

The paper reviews the latest literature comparing air and rail sustainability, assesses whether shifting from air to rail across Europe is a realistic option, and identifies areas where air and rail could be complementary, rather than mutually exclusive. To do so, it seeks to answer the following questions:

• What would be the impact of shifting from air to rail – and how feasible is this?
• What are the trade-offs necessary to get the air-rail balance right?
• In which circumstances would air-rail complemen-tarity work better?

The paper concludes that transportation decarbonisation is more complex than simply planning to shift to rail for travel below 1,000 km. The positive impact on the climate this would have is limited, but it will generate a range of drawbacks.

However, it finds that air and rail have a natural complementarity that should be capitalised on, and recommends that investment be balanced with a view to developing multimodal solutions.

Main Findings

 1. High-speed rail (HSR) has the greatest potential to replace air in the below 500 km category, but this segment, while responsible for 24.1% of European flights, only accounts for 3.8% of aviation emissions – and for geographical reasons, not all of this saving is achievable. In the 500-1,000 km sector, however, HSR has much less ability to substitute successfully for air.

2. By the time it takes to put new HSR infrastructure into operation (18-26 years on average), aviation will be well on track towards reaching net zero emissions by 2050 on its own, in particular with upscaled Sustainable Aviation Fuel (SAF) use, and new propulsion technologies. Transport investment should therefore be carefully balanced between both industries, particularly as aviation decarbonisation will benefit all aviation distance ranges all over Europe, whereas HSR can only realistically impact shorter distances.

3. Studies proposing an air-rail shift underestimate or fail to factor in the significant economic and environmental impacts that a massive expansion of HSR lines would entail, including total lifecycle emissions. This impedes a level playing-field assess­ment as data on the rail market and infrastructure are missing. Even if the 10,000 km of envisaged new HSR lines1 were to be built, HSR will still not be able to match air in terms of connectivity, despite a potential infrastructure investment of around €250 billion2. Massive HSR expansion would also entail significant socioeconomic and biodiversity loss impacts com­pared to aviation, which has limited new infrastruc­ture needs.

4. Rail simply cannot substitute for air in many circum­stances, e.g. islands and regions that are remote or face particular geographic barriers – and for which connectivity is vital to economic survival.

5. Multimodal solutions that combine air and rail are highly attractive in terms of optimising sustaina­bility and improving connectivity, particularly in dense metropolitan areas where HSR infrastructure is already in place. In this sense, both are complemen­tary ways towards meeting emission reduction goals, making the optimal solution more “plane and train” rather than “plane vs train”.