It's called Gephyrophobia: fear of bridges.
The anxiety disorder sends shivers through travelers faced with crossing high bridges that millions of drivers use every day.
National headlines about bridge accidents don't help -- like the collapse of Washington's Skagit River Bridge last May and July's collision that sent a driver and her car tumbling off Maryland's Chesapeake Bay Bridge. Bridge disasters feed larger fears about whether the people we trust to inspect, repair and replace our critical infrastructure are doing their jobs.
"I have this dream about a bridge that goes up and never comes down," a driver told CNN Baltimore affiliate WJZ. "My fear is when I start to feel dizzy that I will pass out."
Treatment varies, says psychologist Dr. Joe Bienvenu of Johns Hopkins University School of Medicine, but sometimes patients can overcome the fear by first imagining themselves traveling over a high bridge and eventually working toward being able to do it in real life.
"Sometimes people get over it very, very quickly," says Bienvenu. Many high bridges offer services to have a driver take frightened travelers and their vehicles safely across.
Actually -- the bridge from the driver's dream isn't so imaginary. There's a real bridge just like it in Maine.
As you approach the nearly 75-year-old Deer Isle Bridge, the road surface appears to go up ... and up ... toward giant, looming green towers. Then, the asphalt appears to simply drop out of sight.
"It's a mystery. That's why you have that concern, you don't readily see what's in front of you" says bridge aficionado Patrick O'Donnell, who's traveled to hundreds of bridges around the world. "You've gotta take it on faith as far as safely getting to the other side."
The Lancaster County, Pennsylvania, husband, father, and cabinet maker has spent the better part of his adulthood seeking out the thrill and beauty of magnificent bridges.
O'Donnell, 48, and fellow bridge aficionado Eric Sakowski have visited more than 1,000 bridges across North America and China.
And sometimes -- when nobody's looking -- they start climbing.
"Everyone says I'm nuts, crazy," laughs O'Donnell when asked about why he does it. He says he only climbs if there are no gates or signs prohibiting it. During a trip to Dent Bridge in Northern Idaho, O'Donnell hopped onto the structure's 24-inch diameter suspension cable on the eastern side of the bridge. On either side of him were handrail cables on which he kept a tight grip while he ascended, step-by-step, up the giant steel cable to the top of the bridge's south tower.
Although the cable isn't flat, "it provides a very wide surface to walk on as long as you have the handrail cables," he says. "I see people climbing these sheer rock face walls -- hanging by their fingertips -- and it's nowhere near as dangerous. But on bridges, if you do slip and fall, the outcome is not going to be good."
It was no more difficult than "climbing monkey bars when you're a kid." Within 10 minutes, he was sitting high above Dworshak Reservoir, with a spectacular view of Idaho's magnificent mountains, including Clearwater National Forest.
He snapped a few photos and paused to wave at fishermen on the smooth lake surface far below. Only a handful of cars passed over the bridge during the half hour O'Donnell spent perched on what he calls "the loneliest suspension bridge in North America."
"I just sat up there and took it all in."
But what about the cops? You'd think these bridge explorers would be worried about getting hassled by The Man -- especially in China, where Sakowski has been traveling a lot lately. He checked out the world's tallest -- the Sidhue River Bridge in Yesanguanzhen, Hubei, China -- in 2009.
Access to unfinished bridges, he says, is less regulated than you might expect. "I'll always take advantage of that and try to sneak onto the construction site and climb up the structure, if I can, to take a picture." Security is low, he says. "It's more of a 'hey, if you get hurt, it's your problem,' type of thing in China."
Several times in the United States, O'Donnell has been accosted by suspicious police driving by in their cruisers. "'Hop in," they'd say, before escorting him back to his car. "Luckily," O'Donnell says, "I've not been arrested."
By his count, O'Donnell has explored 1,103 bridges, including at least two in every state in the union. Although he never followed his boyhood dream of building bridges, he has embraced the subject so much that a conversation with O'Donnell may include terms like "streamlined aero foil deck" or "low-level trestle."
"It's the ability to build these bridges -- that's what fascinates me. The curves and the arches and the technological aspects of what's been accomplished over the centuries."
O'Donnell "has visited more suspension bridges than any person alive in the world," says Sakowski, 47.
The economic downturn put O'Donnell's cabinet-making career on pause. He focused on helping others as a paratransit driver -- transporting the elderly, shut-ins and the physically, mentally and intellectually challenged from their homes to adult day care, shopping, senior centers, work and the doctor.
As for Sakowski, the Los Angeles-based film and video producer began his bridge obsession as a boy by reading the "Guinness Book of World Records." He eventually focused on tracking the planet's lofty bridges and recording them on his site, highestbridges.com.