An artist's rendering of Lex Luthor: Drop of Doom, which is scheduled… (Six Flags )
For most people, a 400-foot free fall from a steel tower is a hair-raising adventure.
Not for thrill-ride enthusiast John Gerard, who can't wait to try what Six Flags Magic Mountain in Valencia is billing as the world's tallest vertical drop ride, set to open Memorial Day.
"I'm really excited about this," the San Diego doctor said. "I think there are many others like me too."
The ride is the latest example of what theme park fans call the thrill ride "arms race," global competition among theme park operators to set world records for speed, height, distance or greatest number of corkscrew turns in a ride.
On the Six Flags ride, dubbed Lex Luthor: Drop of Doom, riders will be strapped into a set of seats attached to a cable that will pull them to the top of a 400-foot tower before they drop to the ground, reaching a speed of 85 mph.
The current record for this category is held by the Giant Drop at Dreamworld in Queensland, Australia, which drops riders from a height of 390 feet. By contrast, the Twilight Zone Tower of Terror ride at Disney's California Adventure peaks at 183 feet.
Thrill rides, Gerard and other enthusiasts say, include roller coasters, drop rides and any extreme attraction designed to frighten passengers. Even an extreme carnival ride might fit the category. Knott's Berry Farm in Buena Park, for example, added a new swing ride last year that hoists riders 300 feet in the air instead of the modest 20 or 30 feet of most carnival swing rides.
Such extreme rides appeal to thrill seekers like Gerard, who says he has ridden more than 650 roller coasters and drop rides around the world. But theme park officials say the rides also boost overall park attendance by sparking a buzz among theme park fans.
"Almost any time that a park invests in something new, there is an impact in guest numbers," said Gene Jeffers, executive director of the Themed Entertainment Assn., a trade group for designers of theme park attractions. "Having something that is the biggest, the fastest or the most extreme doesn't hurt at all."
But how extreme can theme park rides get?
Designers say they will continue to push the limits of speed and acceleration at least until the attractions are so extreme that they no longer attract enough riders to justify the construction costs.
"If you can't get people to ride it, you can't afford to build it," said Alan J. Arena, the founder of A.K.A. Engineering, a Chino company that specializes in theme park attractions. "We are very close to that limit right now."
Perhaps too close.
Thorpe Park, outside London, recently was forced to redesign a new roller coaster called the Swarm after several mannequins used to test the coaster lost limbs on the ride. The coaster, set to open this week, is billed as Europe's tallest winged coaster because riders are strapped to seats that stretch over the side of the rail car, like wings.
ASTM International, a private standards-setting organization based in Pennsylvania, has published a set of standards that spell out the maximum thrust, acceleration and drops for theme park rides. Although the standards are not mandatory in every state, industry experts say most ride designers around the country abide by the ASTM recommendations.
California has adopted some ASTM safety and maintenance guidelines as state regulations but not the standards that set limits on speed, thrust and acceleration.
The 50 pages of guidelines are detailed and specific, spelling out the maximum G-forces that rides can subject riders to under various scenarios, said James Seay, a ride designer and chairman of the ASTM committee on ride standards.
"There is still room for creative engineers to build rides that are unique and operate within those guidelines," he said.
Tim Burkhart, director of maintenance, construction and engineering at Six Flags Magic Mountain, agrees.
"We've got limits on the loads we put into people," he said, adding that the limits won't stop the park from building more rides that set records for thrills.
"Every project I work on, I want to break a record," he said. "I don't care if it's a train ride for kids, I want it to be the longest train ride."
In the thrill ride arms race, world records don't last long.
Top Thrill Dragster, a roller coaster that opened in 2003 at Cedar Point in Sandusky, Ohio, was the tallest roller coaster in the world at 420 feet. Two years later, Kingda Ka, a coaster at Six Flags Great Adventure in Jackson, N.J., broke the record, taking riders to a height of 456 feet.
Thrill ride enthusiasts will point out that Big Shot, a drop ride atop the Stratosphere tower in Las Vegas, lifts riders to a height of 1,081 feet but drops them only 160 feet to a platform along the tower.