Bus problems

There are a significant number of people who view scientists as boffins in white coats who lock themselves in their labs for twelve hours a day while they invent things that are entirely useless to anybody.  This view is somewhat stereotyped, and I hope my blog goes a small way to changing it. (Am I succeeding? – you tell me please).

So needless to say when I find scientific articles that basically support the boffin picture, I tend to put my head in my hands and wonder why I bother. 


This is one (it’s had a bit of airing in internet discussion already). It concerns public transport, and is, for the most part, an entirely reasonable bit of scientific work, except for the hilarious recommendations it makes at the end. The paper concerns the ‘Equal Headway Instability’. In simple English, that’s the phenomenon by which you wait ages for a bus and all of a sudden three turn up at once. Sounds familiar? Maybe you want to substitute trains, trams, lifts (elevators) for the bus, but the same thing happens. And this phenomenon is not just a perception amongst frustrated commuters, it actually happens.

It is well-known (in public transport circles at least) that the bunching of buses in this way is almost inevitable. Basically, it happens because a bus at the front of the group has to keep stopping to pick up passengers (thus slowing it down) but the bus following a minute later finds there are no passengers at the stop, so it carries on, thus catching up the bus in front. Once a group a buses begins to form, it is very difficult to break it up.

In the article, the authors talk about how general the phenomenon is, and analyze (with a computer) different approaches to prevent it. For example, one approach that is commonly tried, is to hold a bus at a stop if it gets there early, giving the bus ahead a chance to get some more distance. The downside is that it annoys those on the bus, who were beginning to think that they might get home early.

Finally, the authors make some recommendations, both to transport system designers, and to passengers themselves. It is the latter set that is somewhat amusing. They focus on preventing delays to buses / trains / lifts etc by ‘good’ passenger etiquette.  Things like ‘Let people off first before boarding yourself’ and ‘Don’t stand around the door area; move further along the carriage’.

Didn’t we know all this already? Do we need a piece of scientific research to tell us that this is utterly sensible behaviour? Anyone who has ever ridden on a city’s underground network will be utterly familiar with such instructions. The authors also suggest a publicity campaign educating users in the Equal Headway Instability, in a manner adapted to the local culture. (And, they hope to test it upon the citizens of Mexico City.) Can you imagine standing on an underground platform in, say,  London, looking across the track to the adverts on the wall opposite, and your eyes fixing upon the one entitled "The Equal Headway Instability"?

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