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University of Iowa News Release

July 19, 2004

UI Study Shows Kids Don't Leave Much Room For Error When Crossing Street On Bike

Bikes provide much-desired independence for pre-teenagers in the summer, but a new University of Iowa study shows that parents should be cautious in deciding when their children are ready to ride independently and where they can ride safely.

The study, which is published in the July/August issue of "Child Development," shows that when crossing busy intersections in a virtual environment, 10- and 12-year-olds select safe gaps in traffic, but they take longer than adults to negotiate the crossing. This leaves little margin for errors, like a foot slipping off the pedal or getting a wobbly start, and potentially places children in danger on the road.

Three professors in the UI College of Liberal Arts and Sciences -- a psychologist and two computer scientists -- combined their skills and knowledge to design an experiment in which children and adults rode a stationary bicycle through a virtual neighborhood, including crossing six intersections.

At each intersection, participants faced continuous cross traffic from the left. The gaps between the cars varied from one and half to four seconds. The 10- and 12-year-old riders chose the same size gaps to cross as adults did, but when they actually crossed, the children left far less time to spare between themselves and the approaching car.

Jodie Plumert, professor of psychology, said that the 10- and 12-year-olds in the study hesitated slightly before making the decision to cross and then took longer than adults to get the bike moving once they made the decision. Individually each factor had only a slight impact on the safety of the crossing, but combined they created an increased risk.

"Although they are making good choices, kids just are not doing the things that result in maximum coordination of movement between themselves and the oncoming car," Plumert said. "Parents need to be aware that their kids may be cutting things close when crossing and work with kids on making better decisions. When teaching children to cross the street on bicycle, parents should know that their kids should select a larger gap in traffic than most adults would choose."

Plumert said the key to this study was her collaboration with Joseph Kearney and James Cremer, both UI professors of computer science. Kearney and Cremer designed the interactive, immersive virtual environment so that participants actually felt as if they were biking through a neighborhood. The virtual neighborhood was projected on three screens placed at right angles to one another, providing a wrap-around view of the environment.

"Using virtual environments we can safely present children with the same kinds of bicycling challenges they confront in the real world," Plumert said. "Being able to study childhood safety without putting participants at risk for injury is a major advance."

Plumert said understanding the underlying causes of bicycle crashes is key to reducing one of the most common causes of severe injuries in childhood. Nearly 500,000 bicycle-related injuries are treated in emergency rooms each year. Motor vehicles are involved in about one-third of all bicycle-related brain injuries and in 90 percent of all deaths resulting from bicycle crashes.

STORY SOURCE: University of Iowa News Services, 300 Plaza Centre One, Suite 371, Iowa City, Iowa 52242-2500.

MEDIA CONTACT: Mary Geraghty Kenyon, 319-384-0011,