* The Kentucky Kingdom theme park complained that a lap bar popped open after the debut of the Thunder Run coaster and that all the bars were subsequently found structurally unsound. A train also uncoupled climbing a hill.
* Houston's AstroWorld added headrests to the Texas Cyclone after a lawsuit was filed by 16-year-old Cesar Gonzalez, whose neck was whipped so badly he ruptured a vein that sent a blood clot to his brain, leaving him half-paralyzed by a stroke.
* Fourteen-year-old Ryan Bielby flew out of the Timber Wolf last year and was killed in the fall. A lawsuit alleges her seat restraints came free; the park said that was impossible. The park was sold this year and the new owners replaced the seat restraints in time for the new season.
It's impossible to tell how many people break their noses or knock out their teeth on rough rides every year. The industry is one of the least regulated and lightly monitored in the country. There are no federal guidelines for the gravitational forces that people pay to be buffeted by, and no coherent monitoring of injuries.
"The biggest problem is nobody keeps any records," said former OSHA inspector Richard McClary, a private amusement-ride inspector and head of the Shelby County Safety Council in Nashville.
"It's exactly the same spot as when OSHA came into industry. Nobody thought it necessary because nobody knew how serious the problems were."
As proof of the safety of its rides, the amusement industry religiously cites the U.S. Consumer Product Safety Commission's survey of emergency-room injuries, which typically estimate only about 7,000 to 8,000 ride injuries annually.
But the statistics don't say how many people got hurt on which rides and at which parks and in which states, nor whether injury counts vary in places with good inspection programs and those with none.
The data also do not include people who seek treatment from their own doctors, a common occurrence.
In fact, the commission annually accepts the industry's estimate of how many people visit amusement parks and divides it by the number of injuries estimated by its emergency-room sample--creating an infinitesimal ratio of park visits to injuries that the industry trots out whenever someone wants to toughen inspections.
Commission spokeswoman Kathleen Begala refused to allow the commission's amusement-park expert, J. DeMarco, to be interviewed by a reporter. DeMarco had said that he would discuss the commission's work if Begala would authorize it.
The industry does have a set of voluntary standards codified with the American Society of Testing Materials, which are updated by an unwieldy 183-member committee that meets only twice a year and is made up of manufacturers, operators, carnivals, theme parks and others with conflicting agendas.
"The standards in our country are probably the most lax standards compared to the British, French or German standards," said Jeffery Abendshien, a private ride-safety engineer in Las Vegas.
Although thrill rides often are dependent on software these days, the American Society of Testing Materials hasn't set standards for computer systems, nor limits on the gravitational forces to which parks can subject patrons. It had trouble deciding on the proper size of park fencing.
"We're getting thrill rides that are more sophisticated. You have a lot more that can go wrong," said private ride inspector Edward Pribonic, a former Disney engineer.
As location is to real estate, the word in the amusement business is capacity. Two trains on one track are better, and trickier, than one.
Nevada's Clark County, the area around Las Vegas that has become a boomtown for casinos crashing the theme-park business, became one of the few governments anywhere to require independent software inspections after it discovered a potentially disastrous glitch while testing the 82-mph Desperado roller coaster at Buffalo Bill's Casino in Stateline, Nev.
"One train had a hole in the software," said county inspection chief David Durkee. "It didn't know another train was on the track during its initial testing."
Typically, a computer is supposed to keep one coaster train from plunging down that first big hill if the other coaster train, for some reason, has stalled on the tracks.
In the case of the Timber Wolf, Dinn said, lightning erased the program near the end of the debut season. He said he fixed the coaster so Worlds of Fun could at least run one train during the last lucrative weekend of a record-breaking year.
But Dinn said the park tried to fix the problem itself in the off-season and overrode the safety system. His account was disputed by Fred Bellemere, the lawyer for Worlds of Fun's owners at the time, Hunt Midwest Enterprises Inc.
Bellemere said the park merely reloaded a computer program Dinn himself sent, presumably the same program that operated the dual coaster trains in the first place.
On opening day the next year, the coaster started out fine. In fact, Jenny Grizzell and her friends rode it 15 times.