Stay the Course

Drivers in heavy traffic often change lanes because they think another lane is moving faster. However, the gains may be an illusion, says Don Redelmeier of the department of medicine and director of clinical epidemiology for Sunnybrook and Women’s College Health Sciences Centre. Wanting to test perceptions of highway traffic speed, he and a group of researchers developed computer models of vehicles travelling on a congested roadway. They found that the next lane appeared to be moving more quickly even if all lanes had the same average speed. They also found that 70 per cent of driving students, who were shown a videotape recorded from a moving vehicle, believed traffic in the next lane was moving faster when it was actually slightly slower. “An awareness of this illusion,” says Redelmeier, “might encourage drivers to resist the temptation to change lanes.”