notes.husk.org. scribblings by Paul Mison.

High Frequency Maps: A London Perspective

Human Transit has recently published a call for public transport systems to use frequency as a base for mapping, which I noticed from this post on Chicago (via mattb on the daily chump).

As a European and a Londoner, the first thing that strikes me is that, for a major city, Chicago has what seems a very poor transport network. The only line that can claim a wait of less than 7.5 minutes on weekdays is a 79th street bus. By contrast, the entire Tube network in London has typical expected waits of about three to eight minutes, dropping as low as almost one train a minute for busy lines at peak.

In fact, the Tube (and, from what I’ve seen, Berlin U-bahn and Paris Metro services) appears to have such little variation that it’s questionable whether such an approach makes any sense. The only thing I think tourists may gain from it is a sense that the Circle line is less frequent than the District and Metropolitan services that it shares tracks with; the deep tube lines would be much of a muchness.

That’s not to say that service variations don’t matter. There’s been a to-and-fro in the tube diagram design ever since it was invented, with dashed lines and, more recently, crosses indicating peak-only lines and interchanges. Currently the map has dispensed with the detail, relegating it to footnotes, but in-car diagrams on the Northern line (one of the most fiddly) do a good job of conveying the way interchanges at Kennington and to Mill Hill East work.

There might be more of a call for it on buses, but one of the most egregious failures noted in the original post (mixing night and day buses) hasn’t been done in London for years, as far as I know. There is a fair bit of variation between very high frequency buses (like the 38 and 73, which should be every minute or three) and those further out in the suburbs which are only every fifteen minutes. On the other hand, putting the entire London bus network on paper takes five maps, four of which are vast; there might not be the room to do it effectively.

One place where frequency is already indicated in London, though, is the Oyster Rail Services map (PDF). However, this used to be done nicely with thin lines for infrequent services and thicker ones for those with more than four trains per hour; now the dreaded cross marks those stations. Still, it does work. (I also recall seeing a map, perhaps by National Rail, that showed the number of trains per hour calling at each station; Clapham Junction and Vauxhall were both up in the 20s, if I’m remembering it right).

Having said all that, I’m still mildly tempted to do something with the idea for London. I can also see that it might well be necessary for US cities; can anyone make one for San Francisco, please?