How bad for the environment are different forms of transport? It is common to assume that air and road travel are much worse than rail. Maybe this is right, but how exactly is it to be calculated? There are many types of environmental impact, and it is not obvious how they should all be taken into account.
Suppose we start with the simplest calculation, and imagine that I have the choice either of staying at home or taking a trip by air, rail or road. Assuming that the train or plane will depart whether or not I am on it, the only cost of my travelling will be the additional fuel needed to carry one person’s body weight (assuming too that the seat would have been empty had I not been occupying it). Calculated this way presumably flying and going by train come out well; driving very badly.
However this line of reasoning looks very superficial. Average, rather than marginal, fuel costs will be very different, and more information is needed – more than I have at present – to calculate average fuel use per passenger per mile, per hour, or per typical journey, for the different modes of transport. But I assume that it is this calculation which is behind the common argument that air travel is, comparatively, so damaging.
Fuel consumption, and the consequent pollution and effects on the climate, are obviously vital considerations. But there are other issues too, such as the cost in terms of resources and energy in manufacturing the plane, car or train, and then of maintaining it. Furthermore, the infrastructure to make such travel possible needs also to be taken into account. Airports, of course, have a huge environmental impact. But planes have the advantage of not needing roads or tracks, both of which are very expensive to produce and maintain. As well as its obvious environmental impact, a road needs ballast, concrete, tarmac and so on, while railways need enormous quantities of steel, timber and gravel, which have to be renewed at intervals.
I’m too lazy to look into relevant research on this, but surely someone must have done? My question is whether there is any research suggesting how to compare different forms of environmental impact, and calculate the comparative average cost of train, air and road travel, mile for mile. Next time I need to travel from London to Scotland what should I do? (I know, I know, I should stay at home in an unheated darkened room …)