The Commons Environmental Audit Committee is not reknown for its sense of humour. So when they said in their recent Report into HS2 that they would like “the government” to “examine the scope for requiring a reduced maximum speed for the trains until electricity generation has been sufficiently decarbonised” they were definitely not joking.
A High Speed train that goes slow? Now there’s a novel idea. The government, after all, could say it has recently switched its case for HS2 away from speed towards “capacity”, so agreeing to put some speed limits on the new trains would not upset that aim too much. So why has the Committee reached this conclusion?
We are told that trains travelling at 225 mph use three times as much energy as a train travelling at 125 mph. We know from using our cars on motorways that cruising at 70 mph uses more fuel than cruising at 50mph, but we of course are stopped from doing anything like current train speeds. That’s partly a safety judgement, and partly an environmental one.
It’s no good saying these are electric trains, so that makes them just fine for environmentalists worried about CO2. A lot of our electricity is still generated from fossil fuels that emit substantial CO2. The more fast trains we run, the more CO2 we will let out into the atmosphere. The Committee also worried about the impact of the new train route on ancient woodland, but did not press on the question of the environmental impact of this railway on urban areas, especially in London. That too could be quite considerable.
People who had not thought through their CO2 accounting rashly assumed trains would be better than cars and planes from the environmental point of view. They had also failed to consider carefully the impact of a new line and the carbon cost of the construction. The CO2 output of the finished railway all depends on how many passengers use the trains, how much energy people use up getting to and from stations, how heavy the trains are and how fast they go. Trains like cars and planes require energy to drive them, and much energy to build them. CO2 accounting is not a simple case of trains good everything else bad.
Nor is the safety case as overwhelming as some believe. Trains travelling at very high speeds are dangerous. As a result the lines have to be completely isolated from any external intervention by people, plants or animals, to avoid items on the line and to avoid any clash with pedestrians, cycles, children playing and anyone else who would be at risk. Motorway carriageways too are segregated from cycles, children playing,and traffic coming in the oppposite direction so they like railway lines are a lot safer than general roads. The speed limit placed on cars at 70mph, allied to rubber tyres with grip and steering systems to avoid collisions means cars have a better chance of keeping safe if a motorway is disrupted somehow. Trains are more likely to plough to disaster at high speed if a train track gets disrupted, as can happen at level crossings or through unplanned access to the tracks by others. Speed limits help reduce accidents on roads, we are told. The same must be true for trains.