Transport maps have become too complex for our brains to understand, according to science

The Tokyo subway map. Easy, right? Image: Tokyo Bureau of Transportation.

As you may have heard (from us, approximately weekly), London's Underground map might just need a redesign. Perhaps adding colours to DLR lines would simplify things. What if the Circle and District lines were shaped like a little penguin? Maybe stations in the suburbs could be more evenly spaced?

But a new study suggests that transport maps not only in London, but in other big cities like Paris, Tokyo and New York, could simply be too big and complex for our brains to easily process - which means no amount of mapping and re-mapping would help.

This idea is based on the fact that, just as researchers estimate that we can only maintain between 100 and 200 friendships at once (this is known as Dunbar's number) there might also be a limit on how much information we can handle while figuring out how to get from A to B. 

Researchers from a variety of institutions concluded in their wittily named paper, "Lost in transportation: Information measures and cognitive limits in multilayer navigation", that we can only deal with around 8 "bits" (i.e. binary, yes/no decisions) at once, and are unlikely to read a map with more than 250 connection points with much ease. In doing so, they're treating our brains a little like you'd treat a computer: figuring out how much processing it can do at once without overloading and crashing. Or, you know, tearing up the map and getting a taxi. 

Part of the issue is that most global cities are now multi-modal - they have subways, buses, trams and even cable cars. While subway maps alone may be simple enough to understand, once you include different modes on the same map, "more than 80 per cent of trips" in New York, Paris and Tokyo are above the 8-bit limit. 

This slightly confusing graph shows that the maps featuring only subway systems (the dotted lines) mostly feature trips under the limit, while most trips on multi-modal maps (the solid lines) go over:

 

As a result, the researchers recommend maps which separate out layers so users can more easily understand them:

...traditional maps that represent all existing bus routes have a very limited utility. This result thus calls for a user-friendly way to present and use bus routes. For example, unwiring some bus-bus connections lowers the information and leads to the idea that a design centred around the metro layer could be efficient. However, further work is needed to reach an efficient, “optimal” design from a user’s perspective.

One example of better map design cited by the researchers are London's "spider bus maps", displayed in bus stops across the capital (you may have squinted at one in the early hours last time you got a night bus with a dead phone). They map out all bus routes proceeding from your current location, so you only see information relevant for your journey, plus they zoom in on the roads around the bus stop. Here's one for Harringay in northwest London:

Click to expand. Image: Transport For London.

This, however, doesn't help you much with longer journeys, or ones involving the Tube. The reality is that most trips in big cities require a combination of modes, especially if you're hoping to use the fastest route possible. As a result, the researchers say that transport in cities has simply become too complicated for our brains to handle on a single map: 

Human cognitive capacity is limited, and cities and their transportation networks have grown to a point that they have reached a level of complexity that is beyond humans’ processing capability to navigate in them. 


Even the attempt to map tangled city networks at all can seem futile, which is why the growth of transport apps and route planning websites is so crucial:

 Indeed, the growth of transportation systems has yielded networks that are so entangled with each other and so complicated that a visual representation on a map becomes too complex and ultimately useless...

The information-technology tools provided by companies and transportation agencies to help people navigate in transportation systems will soon become necessary in all large cities. 

So there you have it: using Citymapper doesn't mean you're lazy. It's just a necessary supplement to your cognitive processing power.  

 
 
 
 

This fun map allows you to see what a nuclear detonation would do to any city on Earth

A 1971 nuclear test at Mururoa atoll. Image: Getty.

In 1984, the BBC broadcast Threads, a documentary-style drama in which a young Sheffield couple rush to get married because of an unplanned pregnancy, but never quite get round to it because half way through the film the Soviets drop a nuclear bomb on Sheffield. Jimmy, we assume, is killed in the blast (he just disappears, never to be seen again); Ruth survives, but dies of old age 10 years later, while still in her early 30s, leaving her daughter to find for herself in a post-apocalyptic wasteland.

It’s horrifying. It’s so horrifying I’ve never seen the whole thing, even though it’s an incredibly good film which is freely available online, because I once watched the 10 minutes from the middle of the film which show the bomb actually going off and it genuinely gave me nightmares for a month.

In my mind, I suppose, I’d always imagined that being nuked would be a reasonably clean way to go – a bright light, a rushing noise and then whatever happened next wasn’t your problem. Threads taught me that maybe I had a rose-tinted view of nuclear holocaust.

Anyway. In the event you’d like to check what a nuke would do to the real Sheffield, the helpful NukeMap website has the answer.

It shows that dropping a bomb of the same size as the one the US used on Hiroshima in 1945 – a relatively diddly 15kt – would probably kill around 76,500 people:

Those within the central yellow and red circles would be likely to die instantly, due to fireball or air pressure. In the green circle, the radiation would kill at least half the population over a period of hours, days or weeks. In the grey, the thing most likely to kill you would be the collapse of your house, thanks to the air blast, while those in the outer, orange circle would most likely to get away with third degree burns.

Other than that, it’d be quite a nice day.

“Little boy”, the bomb dropped on Hiroshima, was tiny, by the standards of the bombs out there in the world today, of course – but don’t worry, because NukeMap lets you try bigger bombs on for size, too.

The largest bomb in the US arsenal at present is the B-83 which, weighing in at 1.2Mt, is about 80 times the size of Little Boy. Detonate that, and the map has to zoom out, quite a lot.

That’s an estimated 303,000 dead, around a quarter of the population of South Yorkshire. Another 400,000 are injured.

The biggest bomb of all in this fictional arsenal is the USSRS’s 100Mt Tsar Bomba, which was designed but never tested. (The smaller 50MT variety was tested in 1951.) Here’s what that would do:

Around 1.5m dead; 4.7m injured. Bloody hell.

We don’t have to stick to Sheffield, of course. Here’s what the same bomb would do to London:

(Near universal fatalities in zones 1 & 2. Widespread death as far as St Albans and Sevenoaks. Third degree burns in Brighton and Milton Keynes. Over 5.9m dead; another 6m injured.)

Everyone in this orange circle is definitely dead.

Or New York:

(More than 8m dead; another 6.7m injured. Fatalities effectively universal in Lower Manhattan, Downtown Brooklyn, Williamsburg, and Hoboken.)

Or, since it’s the biggest city in the world, Tokyo:

(Nearly 14m dead. Another 14.5m injured. By way of comparison, the estimated death toll of the Hiroshima bombing was somewhere between 90,000 and 146,000.)

I’m going to stop there. But if you’re feeling morbid, you can drop a bomb of any size on any area of earth, just to see what happens.


And whatever you do though: do not watch Threads. Just trust me on this.

Jonn Elledge is the editor of CityMetric. He is on Twitter as @jonnelledge and also has a Facebook page now for some reason. 

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