The Strange Dynamics of Airport Walkways
Given that I’m always talking about how traffic can skew our sense of time and perception, I was fascinated by a recent article in the New Scientist that was interested in a simple question: Do the moving walkways at airports actually move people any faster?
Manoj Srinivasan, a locomotion researcher at Princeton University, created two mathematical models of how people travel on such walkways (Chaos, DOI: 10.1063/1.3141428). In the first, he assumed people walk in a way that minimises the energy they expend, a standard theory in locomotion research. In the second, he assumed people walk in a way that best makes sense of the signals relayed from their eyes and legs.
Srinivasan’s models predict that when a person steps onto a moving walkway, they slow their foot speed by about half the speed of the walkway. This suggests that our desires to conserve energy and to resolve the conflict between visual cues and leg muscle signals – your eyes tell you that you are going faster than your legs are taking you – slow us down so that our total speed is only slightly greater than it would have been on regular ground.
This may save energy, but even under ideal conditions of no congestion and no baggage a walkway only makes a small difference in travel time – about 11 seconds for a 100-metre stretch.
Now, granted, this is only a model. But as someone who spends a lot of time in airports, and loves the idea of moving walkways but not often the reality (more on that in a sec), I feel as if there’s something to this. And trying to save travel time at the airport can be a futile, as with traffic: You may blaze down the moving walkway, only to be caught up in a bottleneck at security or the exit doors. And then there’s the reason I so often don’t get on in the first place: I don’t want to have to barge past the people who are simply standing on the walkway, actually going more slowly than normal walking speed (and there’s always a little hiccup of people getting off and on). This is the escalator problem: The technology was designed to move more people more quickly, by augmenting their normal motion, not simply ferrying passive passengers.
But the model above actually has an empirical counterpart, notes the magazine.
The findings help to explain earlier work by Seth Young, now at Ohio State University, who observed travellers at San Francisco and Cleveland airports slowing down on moving walkways, though not as drastically as Srinivasan’s model suggests (Transportation Research Record, DOI: 10.3141/1674-03).
If there is no congestion, people on travelators are marginally faster than on normal ground. However, Young found that the odds that other travellers will block the way are such that on average, it takes longer to get from A to B on a moving walkway.
“Moving walkways are the only form of transportation that actually slow people down,” says Young.
This entry was posted on Tuesday, September 15th, 2009 at 5:54 am and is filed under Congestion, Etc., Traffic Culture, Uncategorized. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.