What is the largest metro system in the world?

Sorry, Paris, you're not even close. Image: AFP/Getty.

This week we've been trying to work out which city has the largest metro in the world. It was surprisingly complicated.

So, for your delectation, here's the whole, horribly over complicated debate.

There are more than 150 metro systems on the planet. Exactly how many, though, is surprisingly difficult to pin down: there's some debate about which systems count, or whether to count integrated networks run by multiple operators as one metro or several.

Working out which metro is the largest is a similarly difficult exercise. Does largest mean “longest”? Most stations? Biggest ridership?

There probably isn't a definitive answer: too much depends on how you understand the question. But what the hell, we've started this now, so this week we're going to look at each possibility in turn. 


Which metro has the most stations?

That looks straightforward enough, doesn’t it? Can’t possibly be any complicating factors here. Right?

Stations are a pretty important consideration when dealing with metros: after all, without places to get on or off, there's not much point in having a train.

And, in this category at least there seems to be a clear winner: the New York Subway has a record breaking 468 stations, roughly three-fifths of which are underground. So, the answer is New York. Here they all are:

A poster listing all New York's subway stations. Image: Alex Daly & Hamish Smyth.

That was easy.

Except, well, looking at things more closely – this got complicated surprisingly quickly – it might not have 468 at all. By "international standards", apparently, it NYC only has 421 subway stations.

So how is there so much uncertainty about whether 47 New York subway stations actually exist? The main reason seems to be that the Metropolitan Transit Authority counts some “station complexes”, such as 14th Street-Union Square, as two or more stations; most networks would count them as one. You'd think it'd be easy to work out how much stations a metro network has, but no, apparently not.

Anyway, what we can say for certain is that the subway has 368km of routes and currently operates 24 services which, we think, is the highest number in the world. It's a pretty big network, is what we're saying here. And that's without counting things like PATH.

Despite the chronic uncertainty over exactly how many New York subway stations there are, it's pretty clear that there are more than on any other network. No other system comes close: the Shanghai Metro is in distant second with its 12 lines and 337 stations, many of which come with fancy features like sliding safety doors.

Platform screen doors installed at Shanghai's Xujiahui Station. Image: Jianshuo/Wikimedia Commons.

Beijing isn't too far behind, with 319 stations, although this seems to run into similar problems as the figure for New York, and a more accurate count may be 268.

Anyway, here’s the whole Top 10, using the figures as given by the networks themselves:

  • NYC Subway – 468
  • Shangai Metro – 337
  • Bejing Subway – 319
  • Seoul* Subway – 311
  • Paris Metro – 303
  • Madrid Metro – 301
  • London Underground – 270
  • Moscow Metro – 196
  • Mexico City Metro – 195
  • Tokyo Metro – 179

You notice that asterisk next to Seoul? That’s because we’re only counting lines 1-9, and not a whole bunch of other stuff that may or may not be part of the network.

Confused? Just you wait until we try to answer the next one:

Which metro is the longest?

You'd think, by restricting ourselves to a simple, one-dimensional numerical measure, that working out which city had the longest metro system in the world would be simple, wouldn't you?


Ha. No such luck. This time (spoilers), the root of the confusion lies in the vexed question of what counts as one metro network.

One oft-cited candidate for the world’s longest metro network is the one in Seoul, which only opened in 1974 but by 2013 included 987.5km of route on 18 lines. That's pretty much enough to get you from London to Marseille. No other city comes close.

So why is this question remotely contentious? Because it's surprisingly unclear whether that metro should be counted as one system or several. It includes lines 1-9, the subway proper, which is operated by the Seoul Metropolitan Rapid Transit Corporation and the Seoul Metro (with which it'll merge next year).

But it also includes routes run by national rail operator Korail. Most contentiously, it includes lines run by satellite cities, such as the Incheon Transit Corporation, which operates trains in, well, Incheon.

 

 

An extract from a map of Seoul's complete metro network created by Wikipedia User IRTC1015. You can see the terrifyingly complicated full version here.

All these operators provide a single integrated network – but it's still the equvialent of measuring the London Underground by counting Overground, DLR, and so forth, or of counting the RER and Transilien as part of the Paris Metro. We are in danger, in other words, of comparing apples and oranges.

So what if you try to stick to apples alone? Look at lines 1-9 alone, and the network measures only 311km.


Which is quite a lot smaller and probably not the biggest in the world at all.

Other candidates for the top slot can’t promise the 900km+ of route that the wider definitions of the Seoul metro do, but the figures they do cite are probably less contentious.

One is the Shanghai Metro, which runs to 548km and counting. In 2013, it achieved the distinction of becoming the first Chinese metro network to cross provincial boundaries, when line 11 was extended into the satellite city of Kunshan in neighbouring Jiangsu province.

There's talk of extending it further, to connect up with metro systems of the cities of Suzhou and Wuxi, both of which are 100km away or more, too. Not bad given that Shanghai didn't open its first metro line until 1993.

It isn't the only monster subway system that's sprouted in China recently either. The Beijing Subway, first opened in 1969, is the country's oldest, so it got a bit of a head start on Shanghai. Today, it runs 18 lines, serves 319 stations, and stretches for 527km.

Schematic map of Beijing's subway, created by Wikipedia Users Ran and Hat600.

This is another one of those networks which has more than one operator: this one's split between the state-owned Beijing Mass Transit Railway Operation Corp (15 lines) and the Beijing MTR Corp (a joint venture with the Hong Kong transit authorities, which operates three). Between them, in 2014, they carried 3.4bn passengers.

One interesting feature of Beijing's metro is its station names, which, translated literally, mean things like Smooth Justice, Heavenly Peace Gate and (less appealingly) Cholera Camp. So, there you go.

Here, best we can tell, with all the caveats about different cities playing by different rules here, is the top 10 of metros proper:

  • Shanghai Metro – 548km
  • Beijing Subway – 527km
  • London Underground – 402km
  • New York Subway – 373km
  • Seoul Subway – 332km
  • Moscow Metro – 328km
  • Madrid Metro – 294km
  • Guangzhou Metro – 240km
  • Mexico City Metro – 227km
  • Nanjing Metro – 224km

Anyway. Next we're going to try counting people. That's where things get really complicated.

Which city has the busiest metro system?

There’s something inherently about awkward about phrases like “1.5bn people a year ride on the Paris Metro”. It doesn’t mean that a fifth of the world are hanging around Châtelet–Les Halles station at least once a year, obviously, it just means that there are that many journeys undertaken.


Anyway. Until very recently, on the question of which metro system carried the most passengers – had the highest ridership, in the jargon – there was a clear winner. The Tokyo Underground Railway Company launched Japan's first underground railway, the Ginza line between Ueno and Asakusa, in 1927. It was just 2.2 km long, but nonetheless, the line became so popular that passengers would queue up, sometimes waiting for over two hours just to ride the metro for five minutes.

Nearly nine decades later, the privately run Tokyo Metro runs nine lines, while the publically-owned Toei Subway operates another four and the Tokyo Waterfront Area Rapid Transit another. Between them they cover 290 stations – and carry a colossal 3.3bn passengers a year, or over 8m a day.

Unsurprisingly, the network has become a byword for overcrowding – a sort of metaphor for Japan's work culture. The concept of “pushers”, in which guards help passengers by shoving them into crowded subway trains, seems to have started in New York. But these days, the “osiyas” (literally, Japanese for “person who pushes for a living”) are associated mostly with Toyko's crowded metro.

Pushers at work. Screenshot from The Fat Finger on YouTube.

At some point in the last couple of years, however, Tokyo may have lost its crown as the world's most crowded. Beijing’s has 18 lines, run by two operators: between them they carried an estimated 3.4bn passengers in 2014.

We say “may” because, as ever, it is difficult to be sure we're comparing like-with-like here: a journey involving two operators and three different lines may be counted once, twice, or three times, depending on the statistical rules applied by the local authorities. At present, then, it's difficult to be sure that Beijing has overtaken Tokyo. If it hasn't, though, it seems almost certain that, in the not too distant future, it will.

Other networks are racing up behind, too. The Shanghai metro only opened in 1993, but in just over 20 years it's expanded to include 327 stations on 14 lines. By 2014 it was already carrying 2.8bn passengers a year. At the end of that year it's believed to have achieved a world record, when it carried 10.3m passengers in a single day.

Not far behind that is our own friend the Seoul Subway, where lines 1-9 carry 2.6bn passengers per year. (The extended network that we talked about last time carries considerably more.)

  • Beijing Subway – 3.4bn
  • Tokyo Subway* – 3.2bn
  • Shanghai Metro – 2.8bn
  • Seoul Subway** – 2.6bn
  • Moscow Metro – 2.5bn
  • Guangzhou Metro – 2.3bn
  • New York City Subway – 1.8bn
  • Hong Kong MTR – 1.7bn
  • Mexico City Metro – 1.6bn
  • Paris Métro – 1.5bn

*Includes the Tokyo Metro, the Toei Subway, and the Rinkai Line.

**Lines 1-9 only

The London Underground is bubbling under in 11th place with just 1.3bn. And you thought the Central Line got crowded of a morning.


So which metro should we call the world's biggest? Is it Toyko for being the busiest? Seoul for its length? New York for its station numbers? Or Shanghai for placing well in all categories?

The answer, alas, has to be “it depends how you count”. Sorry. We did try to warn you.

Research: Suren Prasad.

 
 
 
 

How a Welsh lawyer invented the hydrogen fuel cell – in 1842

A hydrogen-powered bus. Image: Getty.

Let us start, in the spirit of steampunk, by imagining a new and different past. One that is just a little different to that which we currently have.

So welcome to the year 1867. The Victorian age is at its zenith and a new, powerful and monied middle class is looking for things to do with their cash. Towns and cities seem to be growing bigger with each passing day, and horizons are transformed as new buildings appear everywhere.

One aspect of the urban landscape never changes though. Everywhere you look you will see one of the huge gasometers that have been a constant feature of the cityscape for almost 20 years now. They are filled with the hydrogen gas essential to run the fuel cells – or gas batteries, as the Victorians call them – that are so vital for the economy and for powering everyday life.

In both this imagined and the real past, the gas battery was invented in 1842 by a young Welshman from the then town of Swansea, William Robert Grove. It was a revolutionary device because rather than using expensive chemicals to produce electricity like ordinary batteries, it used common gases – oxygen and hydrogen – instead.

However in this timeline, unlike our own, within 20 years the Welsh man of science’s amazing invention had ushered in a new industrial and cultural revolution.

Towering gasometers. Image: Franz Kapaun/Wikimedia

Our imagined scene is the British Empire’s new electrical age. The horseless carriages that run along roads and railways are all powered by electricity from banks of gas batteries. So is the machinery in the factories and cotton mills that produce the cheap goods which are the source of Britain’s growing wealth. The demand for coal to produce the hydrogen needed to run gas batteries has transformed places such as Grove’s own south Wales, where coalfields are expanded to meet the insatiable need for more power.

Middle-class homes are connected to those gasometers through networks of pipes supplying the hydrogen needed as fuel to run all kinds of handy electrical devices. Machines for washing clothes – and dishes – have trebled the workload of domestic servants by transforming their employers’ expectations concerning daily hygiene. There are machines for cleaning floors and furniture. Electric ovens are fast replacing the traditional kitchen range in the more fashionable houses. Gas batteries also run the magic lanterns that provide entertainment for middle-class families every evening after dinner.

Of course, none of this actually happened. The true history of energy, and the culture that depends on that energy, over the past 150 years or so has been rather different. It was coal and oil, rather than hydrogen, that powered the 19th and 20th-century economies.

A curious voltaic pile

The gas battery’s real history begins in October 1842, when Grove, newly appointed professor of experimental philosophy at the London Institution, penned a brief note to chemist and physicist Michael Faraday at the Royal Institution.

“I have just completed a curious voltaic pile which I think you would like to see,” he wrote. The instrument was “composed of alternate tubs of oxygen and hydrogen through each of which passes platina foil so as to dip into separate vessels of water acidulated with sulphuric acid.”

The effect, as Grove described it to Faraday, was startling: “With 60 of these alternations I get an unpleasant shock and decompose not only iodide of potassium but water so plainly that a continuous stream of thin bubbles ascends from each electrode”. Grove had invented a battery which turned hydrogen and oxygen into electricity and water.

The technology described in Grove’s letter to Faraday. Image: Wikimedia/EERE.

In 1842 Grove was busily making a name for himself in metropolitan scientific circles. He had been born in 1811 into a leading family in the commercial and public life of Swansea, and grew up in a world where the importance and utility of science was commonly understood. The Groves’ neighbours included prominent industrialists including pottery manufacturer and botanist Lewis Weston Dillwyn and John Henry Vivian – an industrialist and politician – who were also fellows at the Royal Society.

Grove studied at Brasenose College Oxford before going to London to prepare for a career in the law. While there he became a member of the Royal Institution and it is clear that from around this time he started to become an active electrical experimenter.

Economical batteries

This is when some of Grove’s earliest forays into scientific work began to appear. In 1838 he gave a lecture to the society describing a new battery he had invented: “an economical battery of Mr Grove’s invention, made of alternate plates of iron and thin wood, such as that used by hatters”.

This emphasis on economy was a theme that would recur in his work on the powerful nitric acid battery that he developed a year later – and which led to his aforementioned appointment as professor, and fellowship of the Royal Society – as well as in his work on the gas battery.

Grove described in a letter to Philosophical magazine how the battery “with proper arrangements liberates six cubic inches of mixed gases per minute, heats to a bright red seven inches of platinum wire 1/40th of an inch in diameter, burns with beautiful scintillations needles of a similar diameter, and affects proportionally the magnet”. This is typical of the way battery power was demonstrated. Scientists would show how it could break down water into its constituent gases, make wires glow, or work an electromagnet.

Moritz von Jacobi’s electromagnetic motor, 1873. Image: Wikimedia/Julius Dub.

Significantly, Grove also went on to say that as “it seems probable that at no very distant period voltaic electricity may become a useful means of locomotion, the arrangement of batteries so as to produce the greatest power in the smallest space becomes important”. Indeed, shortly after Grove announced his invention, the German-born engineer Moritz Hermann von Jacobi used a bank of Grove’s batteries to power an electromagnetic motor boat on the river Neva in Saint Petersburg. And the technology later went on to be used extensively by the American telegraph industry.

Born of necessity

It was Grove’s continuing work on making batteries more efficient and economic that led directly to the gas battery which was to be the forebear of the now modern fuel cell. He wanted to find out just what happened in the process of generating electricity from chemical reactions.

It showed how “gases, in combining and acquiring a liquid form, evolve sufficient force to decompose a similar liquid and cause it to acquire a gaseous form”. To Grove, this was “the most interesting effect of the battery; it exhibits such a beautiful instance of the correlation of natural forces”.


The gas battery provided powerful evidence in favour of the theory Grove had developed regarding the inter-relationship of forces, which he described a few years later in his essay, On the Correlation of Physical Forces. There he argued:

that the various imponderable agencies, or the affections of matter, which constitute the main objects of experimental physics, viz. heat, light, electricity, magnetism, chemical affinity, and motion, are all correlative, or have a reciprocal dependence. That neither taken abstractedly can be said to be the essential or proximate cause of the others, but that either may, as a force, produce or be convertible into the other, this heat may mediately or immediately produce electricity, electricity may produce heat; and so of the rest.

In other words, forces were interchangable and any one of them could be manipulated to generate the others.

But what about utility and practical power? Grove clearly believed, as did many of his contemporaries – including the electro-magnet’s inventor, William Sturgeon – that the future was electrical. It would not be long before electromagnetic engines like the one that Jacobi had used for his boat on the Neva would replace the steam engine. It was just a matter of finding the right and most economic way of producing electricity for the purpose.

As Grove put it to a meeting of the British Association for the Advancement of Science in 1866, if:

instead of employing manufactured products or educts, such as zinc and acids, we could realise as electricity the whole of the chemical force which is active in the combustion of cheap and abundant raw materials... we should obtain one of the greatest practical desiderata, and have at our command a mechanical power in every respect superior in its applicability to the steam-engine.

We are at present, far from seeing a practical mode of replacing that granary of force, the coal-fields; but we may with confidence rely on invention being in this case, as in others, born of necessity, when the necessity arises.

He was clear that realising this particular dream was not his problem, however: “It seems an over-refined sensibility to occupy ourselves with providing means for our descendants in the tenth generation to warm their dwellings or propel their locomotives”.

A new past

Grove certainly made no attempt to turn his gas battery into an economic device, but like many Victorians he was fond of looking into the future and putting his technologies there. In many ways it was Victorians such as Grove who invented the view of the future as a different country that we are so familiar with now. Their future was going to be a country full of new technologies – and electrical technologies in particular.

William Robert Grove, circa 1877. Image: Wikimedia/Lock & Whitfield.

By the time Grove died in 1896 commentators were prophesying a future where electricity did everything. Electricity would power transport systems. Electricity would grow crops. Electricity would provide entertainment. Electricity would win wars. It seemed almost impossible to talk about electricity at all without invoking the future it would deliver.

All this brings us neatly back to the new past for Grove and the gas battery that our future technologies may deliver. If the future of new and clean electrical technology – that contemporary promoters of the fuel cell are today offering us – really happens, then the obscure story about a curious little invention by a largely forgotten Welsh man of science will become an epic piece of technological history.

That future, if it happens, will change our past. It will change the ways we understand the history of Victorian technology and the ways in which the Victorians used those technologies to tell stories about their future selves. We should not forget that we still pattern our own projected futures in the same way as they did. We extrapolate bits of our contemporary technologies into the future in the same sort of way.

The ConversationIt is interesting to speculate in that case why particular sorts of technologies make for good futures and others apparently do not. At the end of the 19th century the gas battery clearly did not look like a good piece of future-making technology to many people. It does now.

Iwan Morus, Professor of History, Aberystwyth University.

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