Friday, June 22, 2007
Quite a few people, knowing of my interest in amusement ride safety, have directed me to the coverage of the tragic accident at Six Flags Kentucky Kingdom, where a girl's feet were severed on the "Superman: Tower of Power" drop ride (formerly known as "Hellevator"). The park has removed the ride's page from their website; you can see a cached version at Archive.org.
The ride is an Intamin installation of a "Giant Drop" ride. This is an image from a different installation:
As I understand the ride, each ride carriage is lifted up on three steel cables. (The cables may be attached to a "catch car" that holds the actual carriage, but I think this is one of the ones without the catch car.) After being held at the top, the carriage is released, which falls under the force of gravity to the ground, where it is stopped by permanent magnets, making the ride very nearly foolproof -- i.e., so long as the earth's magnetic force doesn't suddenly change, the carriages will always stop.
But then there's whatever happened here. It is fairly clear that at least one cable broke and either wrapped around the girl's legs or, because of the tension the cables are under, the broken cable flew through her legs. The CNN story says the cable wrapped around her legs.
The other puzzling part is the consistent description of the cable breaking and the carriage falling immediately thereafter. The obvious assumption is that the former caused the latter, but I think for that to happen, it would have to have been a catastrophic failure -- i.e., that all three cables broke at once. My guess (and it's pure speculation) is that the cable braking coincided in time with the point at which the car would have been dropping anyway.
Intamin also manufactured Cedar Point's Top Thrill Dragster, a launched coaster. The cable on that ride has broken periodically, including at least once when shards allegedly injured onlookers, who sued. (Intamin is a very prolific ride manufacturer; my sense is that they have perhaps more than their proportional share of injuries on their rides, including a death at Six Flags New England's Superman: Ride of Steel, but it's hard to be sure.)
More to come as more information becomes available.