TRAIN travel is not always the greenest alternative to flying.
To compare the emissions of 11 different types of transport in the US, Mikhail Chester and Arpad Horvath of the University of California, Berkeley, calculated how many passengers each train, plane, bus or car would carry in its lifetime, as well as how many kilometres it would cover. The pair also took into account emissions produced when creating the associated infrastructure, such as tracks, roads and airports, and how much they would be used.
Overall, cars were the worst climate offenders, beaten only by buses travelling in off-peak hours. But when taking infrastructure emissions into account, train travel – traditionally seen as a greener way to go – came out almost as bad as aircraft. Buildings, tracks and providing power to stations more than double a train’s emissions (Environmental Research Letters, DOI: ).
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Any rail network expansion to encourage people to use public transport should therefore be done cautiously, Chester says, as setting up one used by only a small tranche of the population could generate more emissions than it saves.
Abigail Bristow, who studies transport at Loughborough University, UK, says the study is valuable because it compares all modes of transport on equal terms.