I am grateful to Dr Mayraj Fahim for this link: http://news.yahoo.com/s/afp/20090608/sc_afp/climatewarmingtransportcarbonlifestyle While some dedicated environmental groups have, in the past, audited the environmental impact of the manufacturing process of various goods and means of transport, the practice has not always been given the publicity that it deserves. Now, with scientists looking at public transport, some common beliefs about supposedly "green" transportation are being challenged.
Specifically, the issue about trains is something that I have suspected for some time and I did get into a brief discussion on this at Low Tech Magazine: http://www.lowtechmagazine.com/2008/12/train-travel.html#comments There is no question that trains are at their most efficient at hauling heavy freight or large numbers of people. try and make them luxury vehicles on wheels like they are in the USA, and their efficiency drops. Hopefully, there will be a comparison of the efficiency of local trains in cities like New York with decent public transportation with local commutes as well as with failing, state-owned businesses like Amtrak with cars in long distance travel so that a specific environmental impact in each case is better understood. As far as showing fossil fuels the fist is concerned, I do think that the more efficient the means of transportation, the lower its carbon footprint would be. Let's hope that we get more expert views on this in the near future.