The 52-year-old Irving, Texas, mother of two died of massive head injuries and state transportation workers quickly began examining bridges statewide to see if any other structures were in danger of shedding deadly chunks.
But, in a state where a quarter of the bridges are structurally deficient, it's hard to predict when the next piece of deteriorating concrete will shake free.
In the 41/2 years since Osborn's death 50 miles south of Oklahoma City, more than two dozen other people have filed claims against the state, saying their cars were also hit by pieces of crumbling bridges in Oklahoma, according to information the state provided to The Associated Press under an open records request.
Many of these people said they felt lucky to be alive after being in a fast-moving car thumped by a chunk of concrete.
"It hit the sunroof and bounced down the back side of the car," Mary Selle said. "I thought a small aircraft had fallen on me. If it had happened a second sooner, it could have come through the windshield."
She frequently passes the site of the Aug. 19 accident at 23rd Street and U.S. 75 in Tulsa on her way to her job as a school teacher.
"It could have been a lot worse," she said.
Selle is one of 26 people who have filed claims against the state involving falling concrete since Osborn's fatal accident on June 8, 2004. In all but two of the cases, the state denied the claims, usually saying the claimant failed to show the state was actually negligent. Injuries were claimed in two cases.
Norman Hill, general counsel for the Oklahoma Department of Transportation, said the state is required to inspect bridges every two years. If it has done that, and if it has had no indication of loose concrete on a bridge, it is not liable for damages if a chunk of that bridge should fall, he said.
"You can't fix something before you know it's broken," he said.
Federal Highway Administration data for 2008 show that 5,566 or 24 percent of Oklahoma's 23,587 bridges are structurally deficient, second nationally only to Pennsylvania, which has 6,105 structurally deficient bridges, or 27 percent of its total.
"Theoretically a bridge without deficiencies could lose concrete, but bridges that are structurally deficient are much more likely to do so," said Frank Moretti, director of policy and research for The Road Information Program, a Washington D.C.-based nonprofit organization that promotes transportation policies to improve traffic conditions.
This structurally deficient classification is for bridges that are not necessarily unsafe but require attention for problems that could include deterioration.
"As you would expect, those bridges are more likely to be crumbling literally," Moretti said.
Sometimes structurally deficient bridges can have problems much more significant than falling concrete.
On Tuesday, Dec. 27, 2005, a 45-year-old overpass that had been rated structurally deficient collapsed onto Interstate 70 in South Strabane Township in Pennsylvania, causing three injuries. Other bridge problems in Pennsylvania include a 103-foot-long steel truss that failed in the Dysart area after a snow plow drove over it and the collapse of a small bridge in Economy as a utility truck was driving on it. In Rhode Island, where 22 percent of the bridges are structurally deficient, three cars were damaged on Interstate 295 in the Cumberland area in August 2007, when they drove over a 20-foot-long piece of concrete that fell from an overpass.
In Enid, Okla., a heavily used, 100-foot bridge that was slated for replacement collapsed on March 14, 2007, after a fire truck en route to an emergency call drove over it.
One of Oklahoma's most problematic bridges is a 11/2-mile raised section of Interstate 40 -- a main east-west route through the United States. This section of highway carries 120,000 vehicles a day through the downtown Oklahoma City area, 50,000 more than it was designed for when built in 1965.
The bridge is called "fracture critical," meaning a failure of any number of structural elements would bring down the entire structure.
About a dozen holes open up in the deck of that bridge a year, with concrete sometimes falling to the ground below, said John Fuller, ODOT chief engineer. The bridge is to be replaced by 2012. He said the existing bridge is safe, despite the problems in the road deck.
"We would not hesitate to close it if we thought it was necessary," he said.
Road workers place fencing material under some bridges to catch falling concrete.
Terri Angier, a spokeswoman for the department, said age, traffic load and weather extremes, including Oklahoma's frequent freeze-thaw cycles, work together to stress bridges.
Stephen Ives said a chunk of the Interstate 40 bridge fell on his sport utility vehicle when he was driving on a highway under the bridge in Oklahoma City on July 3.
"It shattered the moon roof of the SUV and that's pretty sturdy glass," Ives said. "If that concrete had hit the windshield we would have been in danger."
"We looked under the bridge afterward and there was a bunch of concrete missing."
For all of the people who file claims for falling concrete, others do not want to go through the process.
On Aug. 7, 2008, Ken Poston was going under a U.S. 169 overpass in Tulsa when a 3-foot by 3-foot chunk of concrete fell inches in front of his pickup truck.
He feels fortunate:
"It was big enough that if it would have been a split second later, I wouldn't be talking to you."
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