Manoj Srinivasan, a locomotion researcher at Princeton University, says that two mathematical models created by him show how people travel on such walkways.
He says that the first model assumes that people walk in a way that minimises the energy they expend, a standard theory in locomotion research.
In the second model, the researcher adds, 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 upon stepping onto a moving walkway, a person slows his/her foot speed by about half the speed of the walkway.
According to him, this suggests that people's desires to conserve energy and to resolve the conflict between visual cues and leg muscle signals-their eyes tell them that they are going faster than their legs are taking them-slow them down so that their total speed is only slightly greater than it would have been on regular ground.
The researcher says that this may be helpful in saving 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.
Earlier, a researcher named Seth Young, presently at Ohio State University, had observed travellers at San Francisco and Cleveland airports slowing down on moving walkways, though not as drastically as Srinivasan's model suggests.
People on travelators are marginally faster than on normal ground if there is no congestion, but Young found that the odds that other travellers would block the way were such that, on average, it took longer to get from A to B on a moving walkway.
"Moving walkways are the only form of transportation that actually slow people down," New Scientist magazine quoted Young as saying.
He believes their main benefit is to reduce walking distance, giving weary travellers a chance to rest.