Which city has the longest metro system?

Is Seoul the world's longest metro? Image: Getty.

This week we're taking a look at the surprisingly complicated question of which city has the largest metro in the world. As with so often with these things, the answer is: it depends how you count.

Yesterday we did number of stations. Today, we're measuring by route length.

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 on 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

Tomorrow: we try to count passenger numbers and things get really complicated.

Research: Suren Prasad.

 
 
 
 

Where did London’s parakeets come from?

Parakeets in the skies above Wormwood Scrubs, west London. Image: Getty.

Visitors to London’s many green spaces would have to be stubbornly looking at their feet to not see one of the UK’s most exotic birds.  Dubbed “posh pigeons” by unimaginative Londoners, these brilliant green parakeets stand out among the fauna of Northern Europe’s mostly grey cities.

‘Parakeets’ is actually an umbrella term referring to the multiple species, which can now be found in London, Amsterdam, Brussels, Paris and various German cities. By far the most common is the Indian ring-necked parakeet, easily recognisable by the stylish red ring around their neck, a matching red beak and, of course, the loud squawking.

In the last 50 years these migrants from South Asia have arrived and thrived, settling into their own ecological niche. In the UK, London is a particular stronghold, but although they may have originally settled in the leafy streets of Twickenham, the birds can now be found in cities as far north as Glasgow.

The story of how they ended up in London is a matter of some discussion and plenty of myth. One often reported theory is that the capitals’ current population are the descendants of birds that escaped from Shepperton Studios during filming of The African Queen, starring Humphrey Bogart and Katharine Hepburn. Others would tell you that they escaped from Syon Park in the early 1970s, when a piece of debris from a passing plane damaged the aviary and allowed them to escape. This chimes with their original concentration in South West London.
My favourite story by far is that they were released by Jimi Hendrix on Carnaby Street in the late 60s. Bored of London’s grey skyline, he set the little fellas free to liven up the place.

However they got here, from 1970 onwards their numbers boomed. In 1992, 700 birds were recorded in London Bird Report. By 1998, 2,845 were seen in the London Area, and by 2006 the ring-neck parakeet was 15th most sighted bird in London.


Darwin would be proud at how well they adapted to the new environment. Toughened up by the hard Himalayan climate, they handle the cold northern European winters better than most locals. Global warming is often brought up in discussions of the parakeets, but it is certainly only part of the story.
It helps, too, that the birds have a 35 year lifespan and few local predators, enabling them to breed freely.

As with any new species, the debate has raged about whether they are harmful to the ecosystem. Strangely reminiscent of the debate over human migrants, often the birds have often been accused of stealing the homes of the natives. The parakeets do nest in tree cavities also used by jackdaws, owls and woodpeckers – but there is little evidence that native species are being muscled out. 

The also provide a food source for Britain's embattled birds of prey. Owls and peregrine falcons have been know to eat them. Charlie and Tom, two city dwelling falcons monitored by Nathalie Mahieu, often bring back parakeets as food.
Of more concern is the new arrivals’ effect on plants and trees. By 2009 their numbers in the UK had grown so much that they were added to the “general licence” of species, which can be killed without individual permission if they are causing damage.

And Parrotnet, am EU funded research project studying the development of parakeet populations across Europe, has warned of the risk they pose to agriculture. In their native India, the parakeets are known to cause widespread damage to crops. As agriculture develops in the UK in line with warmer climates, crops such as maize, grapes and sunflower will become more popular. In India the birds have been documented as reducing maize crops by 81 per cent.

So the parakeets remain divisive. Environmentalist Tony Juniper has disparagingly described them as “the grey squirrel of the skies”. By contrast, the University of York biologist Chris D. Thomas has argued that the parakeets should be left free to move and breed. He sees those wary of the parakeet boom of “irrational persecution” of the bird.

For good or ill the parakeets are here to stay. As so often with migrants of all kinds, there has been some unease about the impact they have had – but the birds, popular amongst Londoners, certainly add colour to the city. Thriving in the urban environment thousands of miles from their natural habitat, they are a metropolitan bird for Europe’s metropolitan cities. 

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