Why’s the Victoria Line so hot?

If you’re a Londoner, you may have noticed that the Victoria Line Tube has introduced new carriages recently. And if you’re a grumpy old git like me, then you might’ve thought:

How come the brand spanking new trains are so much hotter than the old ones? How come travel fares go up way beyond inflation yet the standards have regressed? How is that progress?! ANOTHER TYPICAL BRITISH COCK-UP!!‘ then muttered to yourself about how the country’s declined since ‘my day’ and something about how teenagers are to blame…

Well, I posed this question – not quite in the same words – to TFL, and they gave me this more-in-depth-than-expected response:

“Dear Mr Franklin,

Thank you for contacting us regarding the heat on the new Victoria line trains. I’m sorry if you have found them to be too hot, and as a regular Victoria line user myself I can understand your frustration.

The heat comes from the air in the tunnels, and after a train has been in service for an extended period of time this can cause the carriages to become hot. As the entirety of the Victoria line is underground, ventilated air is normally hot air circulating in the tunnels, as the Victoria line does not have any open sections like the other lines to cool trains down.

Fitting air conditioning to trains for the deep Tube lines is a particular challenge, partly because of lack of space on the trains, but more importantly, because conventional air conditioning systems, like those used in cars, buildings and many trains, would cause even more heat to be created in the very small tunnels, compounding the problem, rather than curing it.

Tackling heat on the Tube is one of the biggest challenges facing London Underground. We are currently doubling the capacity of all the main ventilation fans serving the Victoria line, in readiness for increases in the speed and frequency of train services. We will then install cooling systems above the platforms at four of the busiest stations on the Victoria line, to feed cool air into the tunnels.

On the new trains, there is a regenerative braking system, which means that energy created when the brakes are used is turned into electricity that will go back into the line, thus saving energy.  However, we could not switch on this system until all the old trains, which do not have this system, had been replaced which has only happened in the past couple of weeks. Consequently the energy generated by the brakes on the new trains is being turned into heat which goes into the ventilation system.  Now that the old trains have been removed, we have turned on part of this braking system with it being fully utilised by next spring.

Once again I’m sorry if you find the Victoria line to be too hot, however I hope that you can understand the challenges we face to overcome this issue. Please contact me again if you need any help in the future.

Kind regards…”

I have to say, I was almost impressed.