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Nothing random about 'familiar strangers': Study

Researchers map out patterns of commuters who meet regularly

Published on Jul 22, 2013 7:43 AM
Commuters boarding a bus outside Ngee Ann Polytechnic. Researchers at the Future Cities Laboratory in NUS University Town analysed anonymous ez-link smart card data for a week’s worth of trips and found that on average, a commuter has a one in three chance of seeing the same people the next day. -- ST PHOTO: DESMOND FOO

If that fellow passenger on the bus or train looks familiar, it is probably because you have seen him or her before.

For the first time, researchers here have mapped out patterns involving such "familiar strangers" meeting at the same time and place each day.

Critically, such patterns may hold clues to how diseases can spread in an epidemic.

Researchers at the Future Cities Laboratory, located in the National University of Singapore University Town, analysed anonymous ez-link smart card data for a single week's worth of bus trips.

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Background story


  • Analysed: More than 20 million bus trips taken by some 2.9 million commuters
  • Researchers looked at "in-vehicle encounters" - in which two people were on the same bus at the same time
  • There were 18 million such pairs, repeated roughly once every 24 hours, or at the same time every day
  • 85 per cent of these repeat encounters occurred in the morning, rather than in the afternoon