Are big-city transportation systems too complex for human minds?

February 19, 2016
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Credit: Scott Meltzer/public domain

Many of us know the feeling of standing in front of a subway map in a strange city, baffled by the multi-coloured web staring back at us and seemingly unable to plot a route from point A to point B.

Now, a team of physicists and mathematicians has attempted to quantify this confusion and find out whether there is a point at which navigating a route through a complex urban transport system exceeds our cognitive limits.

After analysing the world's 15 largest metropolitan transport networks, the researchers estimated that the information limit for planning a trip is around 8 bits. (A 'bit' is a binary digit - the most basic unit of information.)

Additionally, similar to the "Dunbar number", which estimates a limit to the size of an individual's friendship circle, this cognitive limit for transportation suggests that maps should not consist of more than 250 connection points to be easily readable.

Using journeys with exactly two connections as their basis (that is, visiting four stations in total), the researchers found that navigating transport networks in major cities - including London - can come perilously close to exceeding humans' cognitive powers.

And when further interchanges or other modes of transport - such as buses or trams - are added to the mix, the complexity of networks can rise well above the 8-bit threshold. The researchers demonstrated this using the multimodal transportation networks from New York City, Tokyo, and Paris.

Mason Porter, Professor of Nonlinear and Complex Systems in the Mathematical Institute at the University of Oxford, said: "Human cognitive capacity is limited, and cities and their transportation networks have grown to the point where they have reached a level of complexity that is beyond human processing capability to navigate around them. In particular, the search for a simplest path becomes inefficient when multiple modes of transport are involved and when a transportation system has too many interconnections."

Professor Porter added: "There are so many distractions on these maps that it becomes like a game of Where's Waldo? [Where's Wally?]

"Put simply, the maps we currently have need to be rethought and redesigned in many cases. Journey-planner apps of course help, but the maps themselves need to be redesigned.

"We hope that our paper will encourage more experimental investigations on cognitive limits in navigation in cities."

Explore further: A mobile guide for buses and trains

More information: Lost in transportation: Information measures and cognitive limits in multilayer navigation, Science Advances, dx.doi.org/10.1126/sciadv.1500445

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11 comments

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Irukanji
not rated yet Feb 20, 2016
No, people over complicate map reading themselves.

You know line 1 intersects with line 8 in 12 stops, so you just ride line 1 until line 8, then jump onto line 8, ride 2 stops, then bus the remaining until you reach your destination.

Google maps street view to familiarise yourself with the final stop, then it's a matter of matching the pictures, which further simplifies reaching the final destination. Or count the stop, but I guess it requires people tobe attentive to their environment and it's clearly not going to happen with their faces jammed in their phones.
Eikka
5 / 5 (1) Feb 20, 2016
You know line 1 intersects with line 8 in 12 stops, so you just ride line 1 until line 8, then jump onto line 8, ride 2 stops, then bus the remaining until you reach your destination.


That sounds simple, until you take into account that the schedules along the lines won't match, so you end up missing your ride and late by 30 minutes.

You don't only need to plot a course through the network, but syncronize the transitions between different vehicles and modes of transport, so that you can actually step from train A to bus B to subway C with enough time to walk between platforms. That is what overcomes human cognition very quickly, and in many cases would be physically impossible in the first place.

Busses are specifically problematic because they tend to not have any clear route maps available, since they may and do change arbitrarily on the whim of city planners.
Eikka
not rated yet Feb 20, 2016
Though I question, in what meaningful sense is the human cognitive limit only 8 bits?

That amount of information is exhausted by a single letter of the alphabet, such as "A" which takes 8 bits to encode in the standard ASCII set. Remembering the name and number of a street correctly contains an order of magnitude more information.

I think there's a confusion here, because you can assign unique identifiers to 256 different point locations using 8 bits of information. Remembering a sequence of four such points is actually 32 bits of information.

promile
Feb 20, 2016
This comment has been removed by a moderator.
Skycrime
5 / 5 (1) Feb 21, 2016
I believe there are issues, especially if we invest in the transportation of the future that we desperately need. The clear answer is to let algorithms do the path finding for us when the trips aren't that simple. Simplifying maps is good, too, but it won't be enough in the long run.
Noumenon
not rated yet Feb 21, 2016
Are big-city transportation systems too complex for human minds?


If we start seeing more raccoons than humans, then probably.

The clear answer is to let algorithms do the path finding for us when the trips aren't that simple. Simplifying maps is good, too, but it won't be enough in the long run.


Sounds like a future project for Google,... take their realtime gps directions and generalize that capability for buses, subway, taxis, etc.

kochevnik
not rated yet Feb 21, 2016
Moscow transport easy to understand, as all routes relate to the centere
Noumenon
not rated yet Feb 21, 2016
Moscow transport easy to understand, as all routes relate to the centere


How many routes do they need to pick up some stale bread and turnips.

kochevnik
not rated yet Feb 22, 2016
I don't know how McDonalds ships their foods

Moscow transport easy to understand, as all routes relate to the centere


How many routes do they need to pick up some stale bread and turnips.
I don't know how McDonalds ships their foods
Eikka
not rated yet Feb 22, 2016
The clear answer is to let algorithms do the path finding for us when the trips aren't that simple.


There's already trip planners for city busses in various cities, and have been for the past 15 years.

You input two addresses and it tells you which bus to take at what time. The trouble is, often there's no bus and you're told to walk 10 miles, or you have to stand around for 30 minutes to wait for the next connection, or run like mad because the app plotted a half-mile dash as a transfer route between two busses only minutes apart, and then in the end it fails anyways because your bus is running late and stopping at every stop, and you get stranded somewhere half-way through.

Then there's tickets. There are arbitrary boundaries where you have to pay more to cross some imaginary line, so you can't travel on a transfer ticket you bought from the first bus. By the time you've got to the third connection you're already paying double what it costs you to drive a car.
Eikka
not rated yet Feb 22, 2016
The above is largely the reason why most public transport customers only do it because they get subsidized: children, students, pensioners, unemployed with benefits etc. basically people who have plenty of time and don't have to pay for it.

There was a leaked document from the local public transportation company that said around 73% of their customer base was on some sort of subsidy or discount. For the rest, it simply didn't make any sense because it took twice as long and cost twice as much as driving (and owning!) a car.

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