Why is the Central line so hot? Science has the answer

After a quick Google, a Drikold system uses Dry Ice which is the frozen solid form of Carbon Dioxide. There would be safety implications of using a Carbon Dioxide system to cool a tube train. Carbon Dioxide is a heaver than air gas as it would need to be a closed system with little or no chance of the Carbon Dioxide being able to escape and gather in low points of tunnel section of track. I would very much doubt that such a system could be installed in the very limited space available on tube stock and there would be issues with recharging the system at terminal stations in a quick and safe manner to avoid service delays.

A good idea, thinking outside the box of normal cooling solutions. But IMHO not practical in a tube environment.

I'm a little confused by all this can it/can't it speculation. I was under the impression that they had said that future tube stock would be A/C.

Is this another error (like the S-Stock introduction timetable) I've picked up from lazy and inaccurate reports in the press?

ETA: Or lazy and inaccurate reading on my part.

I asked about the dark windows on the Central line a while back, and was directed here: previous Central Line tinted windows thread.

The problem with any air cooling/conditioning/refrigeration/heat pump system is that they can only move heat around, and unless the system is 100% efficient (which is impossible) it will generate more heat (somewhere else) than it removes. (Yes, aircon systems actually contribute to the heat wave). So aircooling systems in trains in tunnels will make the tunnels themselves hotter, so further aircnditioning will be required if the stations are not to become unbearably hot. (And of course, every time the doors open the temperatures inside and outside the train will try to equalise, so the job is much harder on a Metro than a long distance service.

But it can work on short distance services - my local line runs a mix of airconditioned and non-airconditioined trains, and the former are noticeably more comfortable in this weather than the latter, despite the warm front invading every three or four minutes (pity about the seats though) - there was actual water running down the outside of the windows yesterday - presumably condensate from the aircon as there was no sign of rain!

If only someone could do something about the heat, oh wait....



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The quick cheap answer to the temperatures on the Central line is to dig cross tunnels to the old Post Office railway, adjacent at several locations and install fans. I've said it before several times but can't get anyone to listen. I know that Whitehall once had a plan to use it as an escape route in case of etc etc, but to hell with the lot of em!

I doubt the passengers would find the Central line too hot today

I wonder though, if you were to take a reading right now of the temperature, what would it be? How well is the heat retained, with no trains moving about, there is static air, but no trains generating heat.

I used to get a (62TS) train that started out of Loughton sidings at about 8.35 am -- unbearably hot summer, as unpainted and east facing . But after that I gather they stabled with doors open both sides?

Northern was the hottest by far then the Bakerloo never went down the Central during the night

Having driven on all 3, I'd go with order of Bakerloo, Northern, central

I rode Mail Rail this summer. The route it uses isn't much more than doing a single loop from the depot, around Mount Pleasant and back to the depot again. This part of the Post Office Railway is the part furthest from the Central Line, I recall it being a fair walk to Chancery Lane to then go on to Stratford.

In the context of this thread, this was one of the hottest days of the year. Not much sooner had we got on the Central, did I want to get off due to the heat. It was crush loaded on a Saturday afternoon, and another passenger was carrying a take-away pizza! This was the same day that Bank was closed for investigating the platforms, so after braving it out past St Paul's, I had to stay on to Liverpool Street. Then we headed upstairs to catch a nice air-conditioned TfL Rail service to Stratford.

I don't know if the Central Line is the hottest, but it was certainly unbearable for me.

The map shows mostly an east-west alignment from Paddington to Whitechapel, but it heads north-east towards Mount Pleasant roughly at Holborn, then back south-east rejoining just west of St Paul's station. Reportedly, Crossrail construction has had to avoid it.

I suspect the idea of using this for ventilation founders on the problem that there are few vents to the surface. Most of the old sorting offices have been sold off - I don't think Bank of America Merrill Lynch, for example (who occupy the former King Edward Building Post Office near St Paul's), would be too keen on having a vent shaft put in. That one is also a listed building.

Also, for ventilation tunnels, you probably want a larger diameter bore so that you can have a large fan turning slowly (quietly, at low frequency), rather than a small one turning quickly (loud, easily audible frequencies). I've walked in ventilation tunnels constructed for the Victoria (at Euston) and Jubilee (at Charing Cross) which are more than twice the diameter, so over four times the cross-section.

A solution is required, I just don't think this is it.