“Mind the Map” – How the map of the London Underground affects decision making

Congestion isn’t just a highway problem. It happens on subway systems, too. Zhan Guo, a professor of urban planning and transportation policy at NYU, says that part of this congestion stems from how transportation authorities draw maps of their systems. In his paper, “Mind the Map” (working paper pdf here), Guo looks at the London Underground system and argues that the Tube map “has a tremendous impact on a passenger’s perceptions and his or her usage of the transit system” since “passengers often trust the Tube map more than their own travel experience on deciding the ‘best’ travel path.” Maps are more than two times as influential as actual travel times, even for experienced transit users. The lesson, Guo says, is that maps themselves can become cost-effective ways to ease planning and operation problems.

Transit maps are not scaled models of physical reality. In the London Underground map, for instance, the correlation between actual distance and transit map distance is just .22. Distance in the Underground map represents just 4 percent of the variation of the actual spatial distance between stations.

This distortion affects travelers’ perceived options of final locations, route choices, and the attractiveness of different routes. The biggest misperception is conflating transit map distance with actual travel time. Transfer stations that look “convenient” can be mobbed by crowds, leading to long wait times. Train trips that look “long” on a map can actually be reached more quickly on foot. Ultimately, travelers “(mis)trust a transit map more than their actual experience; they often take a path that looks shorter on the system map but is longer in reality compared with alternative paths.”

Here is one particular example on the Tube:

There are two alternative paths traveling from Paddington to Bond Street station, path 1 transferring at Baker Street and path 2 transferring at Notting Hill Gates (Map a). Path 2 is about 15% slower by in-vehicle time than path 1, and the Notting Hill Gate station is to the opposite direction of the destination Street (Map b). We would expect that few passengers would choose path 2. However, more than 30% of passengers chose path 2, probably because, on the schematic tube map, path 2 is about 10% shorter than path 1, and Notting Hill Gate station is shown to the south not west of Paddington (Map b).

How should planners adjust maps recognizing the influence they have on travelers’ choices?

There are lots of options. They could redraw maps to better reflect actual distance or actual travel times. They could simply post travel times or draw attention to popular, meaning crowded, transfer stations. Planners could take the focus off individual stations and onto areas. They might note “hot” zones where crowds often form. Travelers who don’t mind a bit of inefficiency in their routes might be willing to take “quieter,” if longer, trips – especially if they have a better chance at scoring a seat. Alternatively, planners might actually remove maps and drive customers to other travel planning options, such as a mobile phone, that can direct them to the most efficient route when travelers type in information about their trip. If the map is always going to influence travelers’ decisions, maybe the best strategy is to lessen travelers’ reliance on any visual version of it?

Addendum: Tim Waters observes: “Its amazing how close everything is. When you are in the tube, the distances seem so much further. I remember a few years ago getting the tube between Leicester Square and Covent Garden! The tube map although great for planning journeys really does distort distances.” Hat tip: Martin Delaney

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  • http://www.markpack.org.uk/ Mark Pack

    Don’t know if you already know this, but the tube map was originally designed in part to deliberately fool people about distances – by making the then new suburbs look less far away and so encourage people to think about living in them.

    • http://www.nudges.org/ Nudge blog

      Did not know that. Very interesting.

    • Tom

      I guess that explains the need for Zone 9! Where have you seen this strategic fooling documented?

      • http://www.markpack.org.uk/ Mark Pack

        Tom: offline I’m afraid in TV documentaries about the tube map.

    • Blogpost

      Mark – I have to take issue with the accuracy of that. The “Beck” map depicted above was not intended to fool people that the suburbs were closer than they really were. The Beck map was designed to simplify the network visually. However, there were predecessor’s to Beck’s map that DID subjectively compress the distance in order to make the nascent suburbs look closer. Not only did it make it easier to fit onto one map the very long distances involved, (e.g. from Baker Street out to Verney Junction in North Bucks) but it also did make it look just a short hop. Even though there were once trains that would serve a full cooked breakfast on the full distance into London each morning.

      • http://www.markpack.org.uk/ Mark Pack

        Blogpost – you’re right, I could have been clearer when I said “the tube map”. Sorry for any confusion.

  • Anonymous

    For the two London Underground options, the number of stations visited & number of interchanges is a better way of estimating the journey time, as the distance over the ground is less important (especially in the central zones 1 & 2). From the example, the quicker route via Baker Street visits 2 intermediate stations, and the slower route via Notting Hill Gate visits 4 intermediate stations.

    Alternative plans do exist that can help make better informed decisions:

    http://ni.chol.as/media/sillytube.html

    Unfortunately the alternative designs are more complicated & not so good in a small sizes. Also, they do not help one decide the best mode of transport.

    • Gawain

      Of course the quickest way is actually Jubilee Line/cross-platform to Bakerloo line at Baker Street/on to Paddington.

  • Kevin Beekman

    There was recently a map design contest for DC Metro where this and other related issues were explored…here’s a lot of discussion about options.

    Map contest winners, part 5: Commuter rail and short turns (May 31, 2011)Map contest winners, part 1: The clean, contemporary design (May 24, 2011)Map contest winners, part 4: Bus lines on the rail map (May 27, 2011)More map contest results, part 1: A geographic base (Jun 2, 2011)More map contest results, part 2: Helpful inclusionsMap contest winners, part 2: Familiar clarity and simplicity (May 25, 2011)

  • Pravjey

    This is why I think tube strikes can be a gift from God…they force us to change our behaviour in light of an obstacle (i.e. walk or travel by bus) and we discover that we don’t need to get the tube for a lot of journeys. Walking and getting the bus can be quite liberating. Kind of a like a reverse Matrix, where one becomes disconnected from the dark network (the Underground) and finds that reality is so much better.

  • http://twitter.com/bentoombs Ben Toombs

    Nice post – you prompted one from me too.  http://bensviews.wordpress.com/2011/06/08/nudges-tube/

  • Mick

    Of course, if they’d build the underground railways properly in the first place, east-west, north-south, or at 45° at a pinch, we wouldn’t be in this mess!

  • Sarah Boyd

    I did this Paddington journey choice today as I tried to get back to South Woodford. I did Notting Hill gate route though as I knew I would get a seat!

  • Anonymous

    Mapnificent (http://www.mapnificent.net/newyork — just an example) shows you how far you can reach, given a total travel time: walking to the subway plus time on the subway plus walking to your final destination, for instance.

  • Mark Noad

    I’ve recently launched a new version of the London Underground map that positions the stations geographically. This resolves some of the issues raised in Professor Zhan Guo’s paper. You can find the map at http://www.london-tubemap.com let me know what you think.

    Mark Noad

  • Mike

    Other factors can affect tube journeys more than actual distance, in particular the amount of time changing from one line to another. 

    At some stations it’s a 10-second hop to an adjacent platform; whereas others are a 10-minute walk to what’s effectively a different station with the same name.