Yesterday I linked to a fine polemic by Kerwin Datu of the Global Urbanist, regarding London's much-imitated wayfinding system. Datu reserved particular scorn for the "spider maps" presented at certain stops and stations, which show you only the bus lines that emanate from there. Maps like this one. (This is actually the west half of a map showing bus routes from the bright yellow area where the map would be posted.)
Datu's quip again:
These maps, which TfL call 'spider maps', fail at the very first task: helping you identify your destination. Normally, once you've found where you're going on a map, you work backwards to where you are. But not here. On these spider maps, you are only shown where the closest bus routes want to take you, not where you want to go. It's like the old joke they tell beyond the Pale: when asking a local for directions one is told, 'well, if that's where you want to go, I wouldn't start from here!'
The maps have many defenders, however, so I should expand on why Datu's polemic resonates with me.
First of all, of course, the London maps only make sense at all in a network where all bus lines can be assumed to be frequent. That's true in inner London but not in many of the systems that imitate it. If we show the customer a big, bright line direct from their location to their destination, we're conveying an impression of physical existence. The bright line looks like a physical thing, like a road, not just the site of an occasional service event. The whole point of Frequent Network mapping, of frequent buses and rapid transit, is that we want people to make exactly that association, to see frequent services as always there ready for them to use.
But when we use such a bright line to refer to an hourly or peak-only or nighttime-only service, we undermine that message and give a misleading impression. Strong lines on the map suggest continuous existence on analogy with rapid transit lines, but these infrequent and short-span lines don't exist most of the time. They are probably not there when you need them.
All that, of course, is part of the case for transit maps that reflect frequency/span categories, both emphasising frequent and long-span services and specifically de-emphasising ephemeral ones like peak-only or night-only services.
But there's a more specific issue with spider maps or "buses from here" maps. They promote single-seat rides while concealing connection opportunities. More generally, they discourage people from discovering how to navigate the complete network.
There are contexts where this is fine. At an outer suburban station where the only bus services are local circulators and links to a few nearby suburbs, the "spider map" allows the customer to see the complete local network without having to find it in a massive map of the whole system.
But there's a different way to organize mapping at stops/stations that might be both more truthful and would help people see more clearly (a) the structure of frequent services that are easy to use even with connections and (b) the necessary detail for all services in a local area. That would be to provide two maps:
- A Frequent Network map for the entire city (or if the city is as big as London, maybe a large subarea of the city). This map would have a prominent "you are here" mark, but its function would to say "here's everywhere you can go from here, on service that's available right now." (You could simplify this map by deleting some Frequent services that would not conceivably be useful on any possible trip from "here," but if you think broadly there usually aren't many of those.) This map would also convey a very useful subliminal message: "here is where you are in your city, and in your network." At least for spatial navigators, this map has a useful long-term value in helping people internalize the network so that they can navigate it more freely and spontaneously in the future.
- A local area map, showing all routes emanating from "here" (or perhaps all routes with those from "here" highlighted) but just out to a radius of several km. The ideal radius is the distance beyond which you should usually be looking for rapid line, possibly with a connection, rather than a local bus line from "here." The local area map should be strongly coded to highlight Frequent services and downplay peak-only and other short-span services.
In both cases, lines exiting the map area should be labelled at the edge with any more distant destinations that you would logically use that line, from "here," to reach. (That may not be all the places the line goes.)
This approach would not lead the customer as precisely as a spider map or "buses from here" map does, but nor would it mislead the customer as much as those maps can sometimes do. Sometimes, the fastest way to get from here to there involves making a connection, but the connection may be very easy and very frequent, and we should resist mapping styles that conceal those opportunities.
That's my instinct, but maybe it's just my prejudice. What do you think?