Wisconsin drivers, listen up: Either look for bikers before you open your car doors or you could soon be ticketed.

The state Senate approved a bill Tuesday requiring drivers to make sure opening their doors would not interfere with traffic or endanger people or vehicles. Those who violate the law could be cited and fined $40, which would grow to $100 for a second offense in the same year.

The plan, expected to be approved by the Assembly later Tuesday and signed into law by Gov. Jim Doyle, also eliminates a requirement that bikers stay at least 3 feet from vehicles.

Supporters say the bill correctly puts the onus on drivers to prevent the common collisions between bikes and car doors. Eighteen other states have laws requiring drivers to not to open their doors before making sure it's safe, according to the League of American Bicyclists.

This week, the group named Wisconsin, which has a strong bicycling culture and many trails, one of the nation's top four bicycle-friendly states. Wisconsin would be the site of the 2016 Olympics cycling competition if Chicago lands the games and is home to several bike companies, including Trek Bicycle Corp.

Lawmakers introduced the bill after a Madison woman fractured a vertebra last year when a motorist opened a car door that threw her off her bike. While 50-year-old Linda Willsey was in the hospital, a police officer gave her a $10 citation for riding too close to the car.

The motorist's insurance company later used the citation to blame her for the accident and try to get out of paying for her health care costs, said Willsey, a pharmacist. The city dismissed the ticket after she fought it.

Rep. Spencer Black, a Madison Democrat who rides his bike to work at the Capitol, said the bill is designed to prevent similar problems.

"There's too many accidents that are caused by the callous opening of car doors," Black said at a news conference outside the Capitol, with hundreds of bicyclists behind him. The bicyclists later met with lawmakers to push for the bill and other bike-friendly laws.

Black said the requirement that bikers stay 3 feet from vehicles was "unnecessary and unsafe." Few bikers follow the requirement, and those who do can be pushed out into traffic, he said.

Randy Swart, director of the Bicycle Helmet Safety Institute in Arlington, Va., cautioned that 3 feet is a good rule that should still be followed. He said getting "doored" is a major safety problem but questioned whether the law would be prevent it.

"My suspicion is it won't help much," he said. "But it certainly will be better than ticketing somebody in an emergency room because somebody 'doored' her. I can understand the sense of outrage."

Some critics, including the Wisconsin Sheriffs and Deputy Sheriffs Association, said a change in the law wasn't needed. Drivers don't need a law to be "more mindful of what they're doing," said the group's lobbyist, Jeffrey Wiswell.

But Matt Wilson, 31, of Madison, said getting drivers to pay more attention is precisely why a law is needed. He said he's had close calls while commuting to work in the suburb of Fitchburg, and one of his friends was injured by a car door last year.

"There's enough dangers out on the roads as it is," Wilson said. "A little care from motorists would go a long way."