In the first place, the railways in total are not a major consumer of energy. Secondly, a huge amount of energy used by the railways is embodied in structures, rolling stock and electrification equipment. Thirdly, any measures that make the use of railways unnecessarily expensive encourage the use of less efficient alternatives.
An immense amount of energy is used up in the manufacture of aluminium railway vehicles and the massive steel electrification gallows and goalposts used to hold up the copper wires, which also takes a lot of energy to mine and refine.
Oddly enough the railways of sixty years ago were probably more energy efficient. Locomotives and rolling stock were kept in use for nearly double as long as today, passenger trains ran at 75 mph and freight trundled along at 15 mph on its own lines, the aim being to keep the trains rolling as far as possible on as few lumps of coal. After 1960, rolling stock has been regularly scrapped prematurely, throwing away between a third to a half of its useful service; the trains themselves were designed so that the small parts that got worn could be replaced as required without scrapping the whole thing.
A further issue with the railways is that the cost of higher speeds tends to get ignored. This does not affect only the energy consumption, but also wear and tear on trains and infrastructure, and the need to design to much higher specifications. The golden range of speeds for passenger trains is between 80 and 100 mph, and for freight, 25 to 50 mph. The lesson has been forgotten.
