Here's everything we learned from an analysis of the colours on every metro map in the world

Pop quiz, hotshot. Where have you seen those colours before?


Too easy? Well try this on for size.


Oh, a wise guy eh? Well what about this?


Alright, alright, I’ll stop. As you obviously know, because that’s the kind of cool dude you are, those are the colour palettes used be three of the world’s most famous metro maps – the London Underground, Paris Metro and New York Subway respectively.

They come from the mildly mind-blowing Global Subway Spectrum, which catalogues the colours of every metro map in the world. It’s all the work of Chicago-based designer Nicholas Rougeux. Here’s his rather nifty explanation of his process.

Taken from Nicholas Rougeux's Global Subway Spectrum. Click to expand. 

The position of the dots on each colour wheel represents the exact shade. Blues are bottom left, greens bottom right, reds at the top; the further from the centre, the darker the shade.

Here’s the full selection from metro maps worldwide:


The version on Rougeux’s site is actually interactive, so if you hover over a colour, this happens:


There’s loads of other stuff you can do with this tool. You can see, for example, that Africa hardly a has any metros:

That’s just three systems, in fact. But Asia has loads:


So does Europe:


You can also view all the colours in this attractive waterfall arrangement:


Or in this interactive 3D graphic, which we frankly have no good way of reproducing on CityMetric, but which is nonetheless very, very cool:

This looks better when it moves, to be honest. 

Lining all the colours up in one place like this highlights the fact that certain colours are more popular. The metro maps of the world are festooned with reds, blues and greens; but there are slightly fewer yellows and purples, even fewer pinks, browns and oranges, and a bare handful of greys.

Least common of all seems to be black, which features in just two networks (London and Bilbao), so if you got annoyed with the Northern Line this morning, take some comfort in the fact that it is in some way special.

Rougeux’s work highlights another point, too. In all, the site categorises 162 different metro networks, and by default it arranges them by the number of colours they use. I counted them, because I do that sort of thing. Here’s the distribution:

Of the 162 networks on the site, only 12 of them uses 10 or more colours, and no network uses more than Seoul, with 15.

Partly this result from the fact that so many metro networks are pretty simple things: 134 of them – the vast majority – get away with five colours or less.

But there’s something else going on here, too. The New York Subway has at least 24 lines (more, if you count the expresses separately); yet it only uses 10 colours.

It does this, I suspect, because a map which uses 24 different colours would not be comprehensible at first glance. You’d need to look carefully to make sure that the blue line you were on, and the one you wanted to get to, were the same blue line.

In other words, thanks to the limitations of both cartography, and the human eye, there is a limit on the number of colours a metro map can use before it gets confusing.

We discuss this on the latest edition of our podcast, incidentally – so you should probably subscribe.

You can find the Global Subway Spectrum here.

Want more of this stuff? Follow CityMetric on Twitter or Facebook.


There isn’t a war on the motorist. We should start one

These bloody people. Image: Getty.

When should you use the horn on a car? It’s not, and anyone who has been on a road in the UK in living memory will be surprised to hear this, when you are inconvenienced by traffic flow. Nor is it when you are annoyed that you have been very slightly inconvenienced by another driver refusing to break the law in a manner that is objectively dangerous, but which you perceive to be to your advantage.

According to the Highway Code:

“A horn should only be used when warning someone of any danger due to another vehicle or any other kind of danger.”

Let’s be frank: neither you nor I nor anyone we have ever met has ever heard a horn used in such a manner. Even those of us who live in or near places where horns perpetually ring out due to the entitled sociopathy of most drivers. Especially those of us who live in or near such places.

Several roads I frequently find myself pushing a pram up and down in north London are two way traffic, but allow parking on both sides. This being London that means that, in practice, they’re single track road which cars can enter from both ends.

And this being London that means, in practice, that on multiple occasions every day, men – it is literally always men – glower at each other from behind the steering wheels of needlessly big cars, banging their horns in fury that circumstances have, usually through the fault of neither of them, meant they are facing each other on a de facto single track road and now one of them is going to have to reverse for a metre or so.

This, of course, is an unacceptable surrender as far as the drivers’ ego is concerned, and a stalemate seemingly as protracted as the cold war and certainly nosier usually emerges. Occasionally someone will climb out of their beloved vehicle and shout and their opponent in person, which at least has the advantages of being quieter.

I mentioned all this to a friend recently, who suggested that maybe use of car horns should be formally restricted in certain circumstances.

Ha ha ha. Hah.

The Highway Code goes on to say -

“It is illegal to use a horn on a moving vehicle on a restricted road, a road that has street lights and a 30 mph limit, between the times of 11:30 p.m. and 07:00 a.m.”

Is there any UK legal provision more absolutely and comprehensively ignored by those to whom it applies? It might as well not be there. And you can bet that every single person who flouts it considers themselves law abiding. Rather than the perpetual criminal that they in point of fact are.

In the 25 years since I learned to drive I have used a car horn exactly no times, despite having lived in London for more than 20 of them. This is because I have never had occasion to use it appropriately. Neither has anyone else, of course, they’ve just used it inappropriately. Repeatedly.

So here’s my proposal for massively improving all UK  suburban and urban environments at a stroke: ban horns in all new cars and introduce massive, punitive, crippling, life-destroying fines for people caught using them on their old one.

There has never been a war on motorists, despite the persecution fantasies of the kind of middle aged man who thinks owning a book by Jeremy Clarkson is a substitute for a personality. There should be. Let’s start one. Now.

Phase 2 will be mandatory life sentences for people who don’t understand that a green traffic light doesn’t automatically mean you have right of way just because you’re in a car.

Do write in with your suggestions for Phase 3.