back to article Research: Airliners can be more eco-friendly than trains

Research carried out by boffins in California appears to have seriously undermined a major piece of received wisdom regarding transport: namely, the belief that railways are more eco-friendly than airliners. The cage-rattling analysis comes from profs at the Department of Civil and Environmental Engineering at UC Berkeley. …


This topic is closed for new posts.
  1. Steve Foster


    I wonder what assumptions about electricity generation were used, and whether any predictions about the effects of improvements in same were made (eg current generation = all fossil-fuel/carbon/GHG-producing = very very bad, future generation = renewables/nuclear, minimal carbon/GHG = very very good).

    I suspect it's going to prove to be easier to upgrade electricity generation than change airliner fuels radically, so the ground-based choice probably has greater potential to be "greenified".

  2. Frank Bough
    Thumb Up

    There's another way to work this out

    Rail is not a popular or growing form of transport because laying tracks is so outrageously expensive. This high financial cost is a major clue as to how 'environmentally' costly rail is. The sad truth about rail is that many of its proponents suffer from the same kind of feeble wooly-headed soft-socialist thinking that drives the green movement.

  3. A B
    Black Helicopters

    But a car...

    It makes sense, but a trains forte is bulk freight or passengers.

    Car drivers should be ashamed if most of their commute is spent in a virtual parking lot. Maybe now we can get the Gov to put trams (or bus lanes) everywhere in the interest of the environment.

    What about helicopters?

  4. Anonymous Coward
    Thumb Down

    Research FAIL

    They're comparing to rail infrastructures which already exist.

    Sure, you want to compare a new airport and flying route to a new rail infrastructure, then fine. But most countries already have a rail infrastructure in place, so this is bollocks.

  5. Dunstan Vavasour

    The inadequacies of carbon counting

    This analysis of the amount of carbon emissions resulting from modes of transport may be valid. But it would appear that the only climate change agent considered is carbon dioxide.

    An electric train uses energy which was converted in a large power station. Such power stations have flue gas desulphurisation in place, so the emissions are almost exclusively carbon dioxide at ground level. An aircraft, on the other hand, is a mobile untreated paraffin stove, which in addition to carbon dioxide emits NOXs, sulphur oxides, unburned hydrocarbons and exotic aromatic compounds straight into the upper atmosphere, as well as seeding clouds (technically a meteorological rather than climatic effect, but one which is chronic).

    The focus on carbon footprint is a godsend for industries with dirty processes, none more so than aviation, giving them the ability to cherry pick a well known measure which makes them look better than they really are.

  6. Eddie

    It's just research..

    For every report that produces this conclusion, you'll be able to dig up another paper that utterly contradicts it's findings. Pick the one that suits your ideology, and go find a soap box, sorry, academic journal, and start pontificating.

    That seems to be the usual methodology.

    They could all easily be summarised as "travel takes a lot of energy, regardless of how you do it"

  7. Steve Foster


    The emissions-saving possibilities for ground-based transport offered through changing the make-up of electricity generation can be seen in the report by looking at the differences between the Caltrain and Boston Light Rail figures. The electricity generation in CA uses less fossil-fuel than that of MA, and the Caltrain has substantially fewer emissions (about 1/3 less), even though the energy consumption is practically identical.

    IOW, "greenifying" power stations would make a huge difference.

  8. Tim Wolfe-Barry

    This makes sense of UK Rail Policy...

    If the railways are only eco-efficient when 100% full, that explains why there are never enough seats & I have to stand for 4 hours from Yorkshire to the South Coast!

    Suddenly a light at the end of the tunnel .... oh, it's an oncoming (and overcrowded) train!

  9. Tim Hughes

    More research failure

    To get to Heathrow for example, I may take the train to London and then the Heathrow Express to the airport!

    Have they considered the use of public transport infrastructures to get to the airport? Those alone would make flying an environmental nightmare.

  10. Roland the Headless Thompson Gunner

    not the first time this has been shown...

    Roger Kemp at Lancaster pointed this out about 5 years ago. See

    This shows how politicians can get whatever greenwash they want by altering a few assumptions. The high speed rail lines they want to build are as bad (in CO2) as modern aviation (unless of course they power the trains by building nuclear power stations). And as a general rule, 3 or more people travelling together could produce less CO2 by taking a reasonably economical car than the train (see also if you don't want to accept Kemp's figures; try Edinburgh-London by train, or 296 miles by car).

    If your pointy haired boss wants to reduce your company carbon footprint from travel, I have a simple 3 point plan:

    1: three or more staff travelling together should go by car

    2: one or two staff should pick the most crowded train service available, which can easily be found by comparing fares and buying the most expensive ticket

    3: if it is not convenient to take a crowded train, staff should fly

  11. TeeCee Gold badge
    Thumb Up

    And, of course, rails.

    It ain't exactly eco-friendly to lay track across huge swathes of the countryside.

    Reminds me of a documentary I saw a while back on the Channel Tunnel rail link. One of the things the programme makers did was toddle off to France to interview their man in charge of track as to how they could stick in a huge high-speed network while we spent years and millions on the "arguing about it a lot" process for one little bit.

    His response was that in the past they'd had carte blanche to stick whatever they wanted whereever they wanted it. However, they'd just gone millions over budget and years behind schedule putting in a line to the west of the country. Apparently some bunch of inconvenient little fonctionnaires had introduced the concepts of planning, approval and environmental impact to what had historically been a simple process. To add insult to injury, they'd also seen fit to allow the peasants to object to having a nice, shiny new railway run through their cruddy little hamlets.

  12. Nick Kew

    @Research FAIL

    It's not just where rail already exists. New projects (such as the channel tunnel was 20 years ago) rapidly repay the environmental cost of building relative to flight, because it transports lots of passengers. It's when a route is scarcely used - a destination in Alaska or Montana (or better still Greenland) rather than in California - that the cost of building a railway (or road) may exceed that of flying.

  13. Lionel Baden

    i know

    Lets just make E trains then they are zero emissio, and cheaper 4p per mile :D

    oh wait hangon !!

  14. Anonymous Coward

    Ac @ 9:29 - not that clear cut

    Take the UK. We have existing rail infrastructure for sure, but it needs almost totally replacing if we are to run TGV stylee fast trains. So the research assumptions do stack up.

    and I'm sure you'll agree that only TGV style fast trains can compete with air travel.

  15. Anonymous Coward
    Thumb Down

    Half full?

    C'mon people - when were you last on a train that was half full?

    The real flaws in the argument are:

    1, airliners don't stop every few miles to let people on or off.

    2, If you take an air journey then you will almost certainly be taking another form of transport at each end as well as the plane itself.

  16. Stuart

    Building Bigger Bridges?

    This is a deeply mysterious report. Since most people get to airports by public transport and in London that means rail (by modern, not Victorian infrastructures).

    Of course building a London to New York railway would be a tad expensive with the wrong sort of jelly fish causing some delay. The shipping alternative is not noted for its green credentials so efficient airliners maybe with some better thought out bio fuels is the best option for intercontinental travel. Instead of 'green' airline taxes that merely deny the poor, but benefit the rich, I always thought that deep and heavy taxes should only be applied to seating over 34". Highly efficient travel (bit of pain which restricts it to really valued travel) for those willing to squeeze in. And, hopefully, an end to the outrageously unenvironmental 'flying beds'. Or at least soak them to finance some decent green research.

    @ FRank Bough - our new railway line opens in 12 months to relieve the growing pressure on the old. Being the East London (Overgound) Line it isn't going to displace any runways methinks ... just make London City Airport more accessible.

  17. Pavlovs well trained dog
    Thumb Down

    get ready

    For Clarkson et al to make huge huffing-and-puffing-I-told-you-so noises.

  18. Steven Jones

    Like with like

    The paper needs a bit more reading, although it is notably thin. However, one thing is blindingly obvious - comparing CO2 footprints for urban transport on a per passenger kilometre basis with that for long haul transport in aircraft is a ridiculous idea. It's not exactly practical to hitch a lift on a 747 for a 5 mile journey into town. By all means compare (say) a high-speed train CO2 footprint with that for a comparable flight (and both should include the relevant parts of the journey that have to be completed by other forms of transport to get to/from the final end points).

    As for flying cars Lewis, then you might as well be talking about flying pigs. The previous Register article on the subject was a joke (like stating that road infrastructure wouldn't be needed, leaving out the little problem of goods movement), safety problems and the objection that many of us would have to these things buzzing around the suburbs. Of course the chance of actually producing such flying vehicles at price points comparable to those of road vehicles is as close to zero as one would care to imagine. At best, expensive toys for the rich.

    Just as with the comitted greenies, another cherry-picked, misrepresentative item chosen to support a pre-decided point of view, rather than a serious contribution. Now there is a valid study to be done over (say) long-haul train vs car, and short-haul public transport vs, say, electric vehicles, but it isn't this study.

  19. Richard Porter
    Thumb Down

    Re: Half full?

    No, the environmental impact of a train or plane is very little different whether it is half full or overcrowded - just a bit more energy needed to drag the extra weight up hills or get it off the ground. But you can't use regenerative braking on aircraft. You can't use the energy fo a landing plane to boost that of one that is taking off. You can do the equivalent with electric trains.

    What does change is the carbon emissions per passenger-km. Overall it doesn't make any difference whether you travel on a crowded train or a lightly loaded one, assuming both trains are running anyway. The marginal impact is the same.

  20. goggyturk

    @ Steven Jones

    "As for flying cars Lewis, then you might as well be talking about flying pigs. The previous Register article on the subject was a joke..."

    <sarcasm>Jeez, you hit the nail right on the head there.</sarcasm>

    If you go and check, the flying car story is in fact a theme spanning quite a few articles that many of us on this site quite enjoy for light relief. Maybe you'd like to complain about the Rise of the Machines (TM) articles while you're at it as well? Or even the BOFH?

  21. Tom

    I'd like to see

    A plane that can run on nuclear power. Rail may be beat by planes in plain CO2 count, if you count it in a particular way, but railways can take advantage of any improvement in electricity generation. It's the same argument as electric cars. While contemporary electricity generation is 'dirty' gas/oil/coal shortages and the green movement will force future generation to 'clean' sources. Railways will adapt to this transition much easier than planes.

  22. omg
    Thumb Down

    Completely mis-reported.

    The report doesn't say aircraft are more eco-friendly at all. Did you even read more than the first paragraph?

    It's clearly shows rail as being generally more efficient per passenger-kilometre.

    Oddly they didn't research long distance rail travel, or ships, which means they don't have any comparison for the large aircraft figures, but anyway, over short distances rail was more efficient.

    Bad reporting.

  23. Liam Johnson

    @Research FAIL

    So you are saying that they never need to replace this rail infrastructure once set up?

    To all the "but, but, but" comments

    I have no idea if this paper is correct or not, but if everyone absolutely believes that rail is so much better, then nobody will bother implementing all your nice ideas for making it even more efficient.

  24. Anonymous Coward
    Anonymous Coward

    @Frank Bough

    "The sad truth about rail is that many of its proponents suffer from the same kind of feeble wooly-headed soft-socialist thinking that drives the green movement."

    And what kind of thinking drives an economic system based on continuous growth on a finite planet, exactly?

  25. Steven Jones


    The article that previous flying car article that Lewis linked to shows no sign of being intended as a joke at all. If it was, it is very cleverly disguised and hats off to him for giving an impression of somebody being serious whilst making what are derisory claims about technology and practicality.

    A bit like that article on how incandescent light bulkbs could be made as power efficient as CFLs after being zapped with a laser. Clearly another joke rather than an inability to understand numbers presented in a misleading manner. Clearly the intention of The Register journalists to have a joke at their reader's expense knows no bounds.

  26. goggyturk

    @ Steve

    Well, everyone else got the joke except you.

    The reason why it came across as serious is because the author seems to be pretty interested in such things for their own sake, which is why I still read his articles... I just take a big pinch of salt with a few of the conclusions he reaches.

    That seems a good rule to use with many of the articles on here.

  27. Emily Parry

    Planes, trains, and flying automobiles

    I can only hope should any of you read the conference paper I'm trying to write at the moment that you can treat my work a little more sypathetically! If the reseachers are venting this paper as a reason for why we should build more planes than trains, than shame on them. More than likely they were just interested in the topic and they are right to point out things nobody else has yet considered.

    We need planes, trains, automobiles (but probably not flying ones - one or two per km, fine, 100s, it's be worse than things are now) and boats. All have niches and specific purposes. Integrating them properly is the key to making them more useful (along with pricing, frequency etc.).

    How could we help prevent the spread of disease, have a universally decent quality of life, avoid long-lasting environmental problems and climate change all at once? LESS PEOPLE. Those fewer individuals would also have to be on the whole smarter, a lot less selfish, and a lot more prideful in their work (whatever it might be) and in the work of others.

    A humanity hivemind perhaps...?

  28. Anonymous Coward
    Anonymous Coward

    Quick skim read

    Suggests that 747s are more environmentally friendly for urban transport than little trains. I cannot wait to see one of them rolling down the North Circular.

  29. Tom

    Assumptions truly are the key

    And let's start right now by straightening out the one obvious mistaken assumption you Brits are making: Unless you happen to be a Senator of more than 12 years from a small state in the northeast corridor, there are no high speed trains in the US, and especially no high speed passenger trains. Rail development here seems to have mostly stopped around the time the robber barons died. Rail in the US means freight: two, three, or more diesels hooked up to a long line of cars carrying coal, iron ore, refined iron/steel, chemicals, automobiles, or perhaps garbage to an out of state landfill. You guys may have the Priusses of trains, here in The States were still driving the Model T.

    Oh, and AC Coward of 8th June 2009 09:57 GMT, in the northeast corridor, even the non-high speed trains are competitive with airlines on trip time after you add in the extra arrival time for security these days. The problem is, while you can hop a commuter flight at just about any 30 minute interval, the trains, well not so much. So travelers tend to fly rather than train.

  30. Steven Jones

    @Emily Parry

    I think you'll find most of the comments are directed at the way Lewis chose to report and headline it rather than the aim of the paper itself. Notably it was headlines that aeroplanes can be more environmentally friendly than trains. Now whilst that is no doubt true under certain cricumstances (building a railway line to supply the research station at the South Pole would clearly be ludicrous as an alternative to using 'planes), the comparison he chose to make was a completely bogus one. Either he was being stupid or provocative (I suspect the latter).

    Now as for your wish for fewer people (and, for that matter, mixed transport modes), I'd echo that - but I'd be interested to know how you plan to achieve that aim. We have to start where we are. I rather suspect that nature will do it for us - I'm just hoping it's sufficiently far into the future that I'm not around to witness it...

  31. Anonymous Coward
    Anonymous Coward

    Impact per passenger km is a bogus statistic

    It would only be relevant if the mode of transport in question was 100% full.

    A train (or plane) with 1 passenger on it does pretty much the same environmental damage as a full one. Yet the Kg of CO2 per passenger Kilometre would be significantly different.

    So, given this metric, the best way to save the polar bear is to hire transients to take up any unused spaces on planes / trains / buses so they are always full. CO2 / passenger / KM drops, ice caps re-form, polar bears get back to eating Eskimos and all would be well in the world.

  32. Martin Silver badge

    per passenger km

    It's going to make congestion in London a lot worse if they have 747s taxiing down the buslanes torepalce the tube.

  33. Anonymous Coward

    I'd love to fly the Central Line

    to Tottenham Court Road.

    But I get the kinda feeling that a few skyscrapers and lack of landing space in central London just might kybosh the whole thing.

  34. gollux

    And yet...

    How do you fly from one end of Boston to the other, so you can get this increased efficiency.

    Apples and oranges.

  35. Eddy Ito

    How very odd

    To me this is totally unexpected given that Berkeley is usually the most leftish, greeny, french kiss a gopher's hole, antiestablishmentarian, with liberally and social justice for all, kind of place. Oh my, the times they are a changin', into what I can't say, but there you go.

    As far as trains here go, flying is usually cheaper, assuming you fly cattle class, and gets you closer to where you really want to be. I'd love to have a train like the HST in Taiwan but in the US, where would you run it? You'd have people saying it's too fast, too expensive, too loud, too dangerous, NIMBY especially if it isn't going to stop here, too et cetera.

    Oh Lee, the best way to save the polar bear is to stop shooting the buggers. Unless of course you're talking about 1/2 oz creme de cacao mixed over ice with 1/2 oz peppermint schnapps, strain into a shot glass. Enjoy.

  36. Anonymous Coward Silver badge
    Anonymous Coward

    Boston Light Rail

    A bit hard to judge by the transit maps, but I'd guess damn few commuter airline routes are as short as the likely longest runs on the Boston light rail system.

  37. Rick

    Flying cars

    Lewis - Did I miss it, or did you fail to account for the adverse air-quality effects and the, um , "environmental impacts" of all the crashing and burning the flying cars?


  38. Charles Manning

    Different tech for different purposes

    Airliners can be more efficient on long haul perhaps, but that is only because the huge take-off cost can be offset by a long cruise time.

    A 747 uses more fuel in take off as it does in an hour of cruising. On shorter distances, up to say 500km, that really messes up the numbers.

    Use trains for commuter transport and aircraft for long haul.

This topic is closed for new posts.

Other stories you might like