Anne Irvine doesn’t step into a roller coaster–she leaps. She grabs the handle and swings her legs into the car like a vaulting gymnast. “Woo-hoo!” she shouts as she lands in the backseat of the Millennium Force.

It’s a hot and sticky July evening at Cedar Point, and Anne and her husband, Brian Ondrey–self-described thrill seekers and coaster nerds–are showing me three of the Ohio park’s “most fast and intense” coasters. I’ve never been here before. “Don’t worry,” Brian assures me, “the first drop is utterly terrifying, but after that it’s fine.” I follow Anne’s lead and throw my hands up during the ride and catch some “air time” from the backseat, smiling most of the way.

Brian and Anne, who met through the American Coaster Enthusiasts and married five years ago, have ridden hundreds of different roller coasters between them–and have made their favorite hobby their life’s work. Two years ago, they started Irvine Ondrey Engineering, an Ann Arbor company that designs safety control systems for amusement park rides. The business combines Brian’s two decades of engineering experience with Anne’s marketing prowess for what Brian calls the industry’s “secret cool job.”

Anne, thirty-four, grew up in the Ann Arbor area with season passes to Cedar Point in Sandusky, Ohio. Her passion for the park earned her the nickname “CP.” Brian, forty-one, was raised in Pittsburgh, just ten minutes from Kennywood amusement park, where he worked as a college student.

When Anne was fourteen and waiting in line to ride Cedar Point’s Raptor coaster for the first time, she had a revelation: she wanted to become the amusement park’s first female president. Her parents set up a meeting with Cedar Point’s CEO, who encouraged her to keep learning about the industry–and to get a good education. Homeschooled through Ann Arbor’s Clonlara, she says she learned to be a “self-starter and stay dedicated to my passion,” eventually earning a marketing degree from Eastern.

Brian got his electrical and computer engineering degree from Carnegie Mellon. After starting out in the steel industry, he landed a job at a large Baltimore-area engineering firm that specialized in amusement park rides. He worked on rides in England, Taiwan, China, and across the United States. He and Anne corresponded by email for a few years before arranging to meet at Cedar Point in 2001. They had “an instant connection,” Anne says. She became his intern and traveled with him.

In 2004 Brian moved to Ann Arbor, a place where Anne says “everyone is free to be themselves–it doesn’t matter how outlandish or eccentric you are.” When he realized there was “no room left to grow” at his company, he and Anne decided they’d start their own. People told them it was too risky. “But my dad said, ‘I know you can do this–I know this is your time,” Anne says. Brian took an entrepreneurial course through SPARK, the economic development group, and the couple incorporated as a woman-owned business.

Working from their south-side home, Anne and Brian now field phone calls from places as far-flung as Switzerland, Idaho, and Myrtle Beach, South Carolina–and are ready to travel at a moment’s notice. They will troubleshoot a problem on a roller coaster, retrofit an old ride, or help build a new one from the ground up. Brian explains that creating a new ride is like “putting together a jigsaw puzzle.” The manufacturer has a vision of the ride, and Brian puts the pieces together to make it work. He writes the ride’s computer program and plans components including sensors, brakes, control boxes, and electrical wiring.

IOE’s first projects included two new wooden roller coasters for Great Coasters International in Florida and California, as well as Lightning Run, a prototype coaster by Chance Rides in Louisville’s Kentucky Kingdom. Anne and Brian worked sixteen-hour days for two weeks testing and fine-tuning the ride so it would be ready for the park’s opening day in May.

The two are “extreme night owls,” a good fit for an industry that handles maintenance at odd hours. In their spare time, they ride horses (Anne is a jumper and owns a horse named Top Thrill, after a Cedar Point ride), and they’re trained weather spotters. They don’t have kids, but Anne calls herself “an eternal child” and collects My Little Pony figurines. Brian is an avid gamer. During the summer they visit Cedar Point weekly if they’re not on a job.

Anne says that rides are designed “to give the illusion of being out of control” but actually are built with redundant systems and “zero tolerance” for error. The chance of being seriously injured at an amusement park is just one in 24 million visits, according to a 2011 trade group study. But by the time we finish our second ride at Cedar Point, on Maverick–a coaster that’s modeled after a runaway horse–I show signs of being out of control: there’s slobber on my face, tears in my eyes, and goose bumps on my legs.

The fastest coaster rides, Brian and Anne say, are at “nighttime in the summer right after a thunderstorm on a hot day”–the tracks are slipperier when wet, and time and heat soften the grease in the wheels. To “maximize the thrill,” experiment with riding in different seats (third row in the Magnum coaster is the “ejector seat”). But even they have their limits: spinning rides make Anne sick, and Brian, who’s had to climb roller coasters for safety checks, admits he’s afraid of heights. “Some people really shouldn’t ride,” says Anne, “because of health conditions … The ride warnings are there for a reason.”

As the sky darkens over Cedar Point, there’s one more ride on the hit list: the Top Thrill Dragster. Anne’s favorite, it looms in the distance, rising 420 feet. The ride’s been shut down since morning because of high winds, but at 9 p.m.–an hour before the park closes–I hear a shriek from Anne. It’s running again. “There is nothing that matches it in intensity,” Anne promises as we speed walk across the park to get in line. “It will drag you by the gut and pull you!”

After an hour’s wait, we reach the ride platform, which looks and feels like a late-night party. Music is blasting, and people are singing along to the lyrics: “From the rooftops shout it out … baby I’m ready to go!” We enter the front seat–“the only way to ride this,” insists Anne, who’s done it nearly 400 times.

I take a deep breath and brace myself. We lurch forward and blast 120 mph to the top, where we pause briefly for a surreal view of the entire park–and then a frightening plunge straight down. Seventeen seconds after our launch I realize that I am indeed still alive, and we walk through Dragster’s exit gates.

Anne turns to me with a big grin and gives me a high five. “Once you do this,” she tells me, “you can do anything!”