Jon Hilkevitch

Almost 1 out of 5 drivers in Chicago are likely violating the city's nine-year-old ban on using hand-held cellphones while behind the wheel, according to a state study that prompts questions about whether a new and stricter Illinois law will reduce accidents caused by distracted driving.

Chicago had the state's highest rate of drivers visibly using electronic devices to either talk on the phone or send or read text messages, according to the statewide study conducted by the Illinois Department of Transportation.

"The survey really told us a lot about what is going on every day,'' said John Webber, IDOT's communications director and the department's former interim director of traffic safety. The observational survey of more than 33,000 drivers was done on busy state highways, local roads and residential streets, officials said.