Which is London’s hottest tube line?

Temperatures on the tube in August 2013. Image: TfL.

So which underground line is actually the hottest?

This is the sort of question that holds only idle interest for most of the year, but becomes pretty much life-and-death during a heatwave. Like, for example, the one we’re in the middle of right now.

This week, especially on Wednesday, it’s predicted to be so hot that some route re-jigging may be necessary. As noted by the Evening Standard last year, parts of TfL’s public transport network, can, in the summer months, break the temperature beyond which its illegal to transport cattle. Which is less than ideal.

But some sections, of course, are hotter than others. Using a combination of hard facts, science, intuition, and a bit of guesswork, we've ranked the tube lines from hottest to coolest – or, from those you should avoid at all costs, to those where there's a passing chance you might be able to breathe. Here they are: 

How we did it

The temperatures on board the tube rely on a lot of different factors: the size of the tunnel, its depth, the ventilation available, and the number of trains and people bustling through it. 

One factor, though, tends to override the rest: air-conditioning. Air-con is widespread across the Metropolitan, Hammersmith & City, and Circle lines, which makes them, as a rule, cooler than the Underground network (it's currently being introduced on the District Line, which makes it a little warmer than the others on average). 

All four are also "sub-surface lines", meaning they're far closer to the surface than the rest of the network, occasionally pass through above-ground stations like Barbican, and are generally just better ventilated. All four lines are also introducing walk-through trains: that, too, will improve airflow through the trains.

Air conditioning is also operational on a fair number of Overground trains. The combination of being above ground and air-conditioning puts the Overground in first place, in our opinion (though on an extremely hot day the disadvantages of being in direct contact with sunlight could outweigh the advantages of fresh air). 

The DLR is next: it, too, operates almost exclusively above ground, and stops so often that heat doesn't have much of a chance to build up. Plus, you get to feel like you're driving the train. But – no air con.

Then, we get to what are called the "deep level" lines.These are where things get really steamy, thanks to the depth of the tunnels and the thinness of both tunnels and trains.

You can't install air conditioning on these trains: there isn't enough space in the carriages, and besides, there's nowhere for the heat to actually go once the air-con tries to release it. You'd just turn the tunnel into a heating pipe.

Ranking these lines took a little more guesswork. First, here's a heat map of central London provided to us by TfL, which shows the average daytime temperatures at the end of platforms throughout August 2013: 

Image: TfL. 

The Jubliee line, despite hosting some of the deepest tunnels in the network, does best out of these lines: as you can see on the map, it manages to stay coolest, thanks in part to fans which cool the stations' ambient temperature during the night. (The fact it's a relative newcomer, a large chunk of which was built in the 1990s, probably helps.)


Next up is the Victoria line, which was actually one of the hottest lines on a 2006 version of the map shown above. Since then, TfL has managed to cool it down using "regenerative braking systems" on its trains, which convert the friction of braking back into the power supply, rather than into heat; as well as the regeneration of the line's 50-odd ventilation shafts. New trains on the Victoria line also ventilate carriages by pulling up air from the base of the tunnel into the carriage at passengers' head height. 

The Waterloo and City line is, to be honest, a bit of a mystery. TfL's map doesn't give much information on its temperature, though platforms at Waterloo and Bank are both quite cool. We suspect, though, that a calculation of average daily temperatures don't mean much on a line which used mostly at commuter times.One final clue is that it runs four-car trains, not six, which could reduce the temperature – so we've given it the benefit of the doubt and put it in fifth place. 

The Northern line was once famed for its roasting conditions, but, like the Victoria line, recent ventilation improvements and new regenerative brake systems have lowered temperatures considerably over the past five years or so. Things still get a little sticky around Charing Cross and Bank, though. 

The Piccadilly and Bakerloo lines haven't had the same cross-network cooling mechanisms put in place, so they're still hitting the high 20s or even 30°C in summer months. A TfL spokesperson told me that high speed fans have been installed at Bakerloo platforms at Lambeth North and Marylebone to tackle the heat, though we're assuming that was after this map was made:

And finally, we come to the big hitter. The Sauna line. The line where 30°C starts to feel positively breezy. Appropriately enough, the hottest line is the red-hued Central line – something you can on the map above, and which is backed up by more anecdotal evidence:

This, presumably, is thanks to the Central Line's deep, low-ceilinged trains, plus the fact that TfL hasn't introduced any coolling mechanisms on the line over the past few years. 

The Central Line's Twitter feed has this helpful advice for travellers on the sweltering trains:

We have some more: avoid the Central line at all costs. Seriously. Science says so. 

 
 
 
 

Seven climate change myths put about by big oil companies

Oil is good for you! Image: Getty.

Since the start of this year, major players within the fossil fuel industry – “big oil” – have made some big announcements regarding climate change. BP revealed plans to reduce its greenhouse gas emissions by acquiring additional renewable energy companies. Royal Dutch Shell defended its $1-$2bn green energy annual budget. Even ExxonMobil, until recently relatively dismissive of the basic science behind climate change, included a section dedicated to reducing emissions in its yearly outlook for energy report.

But this idea of a “green” oil company producing “clean” fossil fuels is one that I would call a dangerous myth. Such myths obscure the irreconcilability between burning fossil fuels and environmental protection – yet they continue to be perpetuated to the detriment of our planet.

Myth 1: Climate change can be solved with the same thinking that created it

Measures put in place now to address climate change must be sustainable in the long run. A hasty, sticking plaster approach based on quick fixes and repurposed ideas will not suffice.

Yet this is precisely what some fossil fuel companies intend to do. To address climate change, major oil and gas companies are mostly doing what they have historically excelled at – more technology, more efficiency, and producing more fossil fuels.

But like the irresponsible gambler that cannot stop doubling down during a losing streak, the industry’s bet on more, more, more only means more ecological destruction. Irrespective of how efficient fossil fuel production becomes, that the industry’s core product can be 100 per cent environmentally sustainable is an illusion.

A potential glimmer of hope is carbon capture and storage (CCS), a process that sucks carbon out of the air and sends it back underground. But despite being praised by big oil as a silver bullet solution for climate change, CCS is yet another sticking plaster approach. Even CCS advocates suggest that it cannot currently be employed on a global, mass scale.

Myth 2: Climate change won’t spell the end of the fossil fuel industry

According to a recent report, climate change is one factor among several that has resulted in the end of big oil’s golden years – a time when oil was plenty, money quick, and the men at the top celebrated as cowboy capitalists.

Now, to ensure we do not surpass the dangerous 2°C threshold, we must realise that there is simply no place for “producers” of fossil fuels. After all, as scientists, financial experts, and activists have warned, if we want to avoid dangerous climate change, the proven reserves of the world’s biggest fossil fuel companies cannot be consumed.

Myth 3: Renewables investment means oil companies are seriously tackling climate change

Compared to overall capital expenditures, oil companies renewables’ investment is a miniscule drop in the barrel. Even then, as companies such as BP have demonstrated before, they will divest from renewables as soon as market conditions change.

Big oil companies’ green investments only produce tiny reductions in their overall greenhouse gas emissions. BP calls these effects “real sustainable reductions” – but they accounted for only 0.3 per cent of their total emissions reductions in 2016, 0.1 per cent in 2015, 0.1 per cent in 2014, and so on.


Myth 4: Hard climate regulation is not an option

One of the oil industry’s biggest fears regarding climate change is regulation. It is of such importance that BP recently hinted at big oil’s exodus from the EU if climate regulation took effect. Let’s be clear, we are talking about “command-and-control” regulation here, such as pollution limits, and not business-friendly tools such as carbon pricing or market-based quota systems.

There are many commercial reasons why the fossil fuel industry would prefer the latter over the former. Notably, regulation may result in a direct impact on the bottom line of fossil fuel companies given incurred costs. But climate regulation is – in combination with market-based mechanisms – required to address climate change. This is a widely accepted proposition advocated by mainstream economists, NGOs and most governments.

Myth 5: Without cheap fossil fuels, the developing world will stop

Total’s ex-CEO, the late Christoph de Margerie, once remarked: “Without access to energy, there is no development.” Although this is probably true, that this energy must come from fossil fuels is not. Consider, for example, how for 300 days last year Costa Rica relied entirely on renewable energy for its electricity needs. Even China, the world’s biggest polluter, is simultaneously the biggest investor in domestic renewables projects.

As the World Bank has highlighted, in contrast to big oil’s claims about producing more fossil fuels to end poverty, the sad truth is that by burning even the current fossil fuel stockpile, climate change will place millions of people back into poverty. The UN concurs, signalling that climate change will result in reduced crop yields, more waterborne diseases, higher food prices and greater civil unrest in developing parts of the world.

Myth 6: Big oil must be involved in climate policy-making

Fossil fuel companies insist that their involvement in climate policy-making is necessary, so much so that they have become part of the wallpaper at international environmental conferences. This neglects that fossil fuels are, in fact, a pretty large part of the problem. Big oil attends international environmental conferences for two reasons: lobbying and self-promotion.

Some UN organisations already recognise the risk of corporations hijacking the policy-making process. The World Health Organisation, for instance, forbids the tobacco industry from attending its conferences. The UN’s climate change arm, the UNFCCC, should take note.

Myth 7: Nature can and must be “tamed” to address climate change

If you mess with mother nature, she bites back. As scientists reiterate, natural systems are complex, unpredictable, and even hostile when disrupted.

Climate change is a prime example. Small changes in the chemical makeup of the atmosphere may have drastic implications for Earth’s inhabitants.

The ConversationFossil fuel companies reject that natural systems are fragile – as evidenced by their expansive operations in ecologically vulnerable areas such as the Arctic. The “wild” aspect of nature is considered something to be controlled and dominated. This myth merely serves as a way to boost egos. As independent scientist James Lovelock wrote, “The idea that humans are yet intelligent enough to serve as stewards of the Earth is among the most hubristic ever.”

George Ferns, Lecturer in Management, Employment and Organisation, Cardiff University.

This article was originally published on The Conversation. Read the original article.