It starts with a sudden surge of fear. The palms begin to sweat, the heart races uncontrollably. Panic strikes. The driver clutches the steering wheel in terror, frantically searching for the exit sign.

Welcome to Washington's ring of fear -- the Capital Beltway.

"It's an utterly frightening experience," said one Silver Spring housewife. "The last time I drove on it was six years ago. I'll never do it again."

Driving on the Beltway, the 66-mile circular suburban artery that opened in 1965, has become one of the most common and crippling anxieties in the Washington area.

In fact, experts say, it is second only to fear of flying.

"The Beltway is a composite phobia," said Dr. Robert L. DuPont, director of the Phobia Program of Washington. "It encompasses many fears: the fear of being away from home, fear of bridges, fear of high speed merging fear of high speed trucks, fear of being trapped."

For some, that fear translates into a slight case of the jitters. For others, it causes a "panic attack" in which the driver feels a loss of control, experiences heart palpitations, perspiration and blurred vision. The Beltway becomes a phobia and the driver learns to control the fear by avoiding the highway altogether.

"The first time I felt it, I was on 270 coming from Montogomery Mall," said Wilhelmina Schendeler. "I felt this surge of fear. I had it twice more on my way to Dulles Airport."

Schendeler first avoided driving on Interestate 270. Then stopped driving on the Beltway. "Since I lived in Gaithersburg, I couldn't go very far. It bothered me a great deal."

She went to a psychiartrist. "It's nice to talk about yourself, but it didn't do anything for my driving," she recalled. "I was diagnosed as having a neurosis. He never mentioned the word phobia."

For two years, Schendeler refused to drive on the Beltway. "I didn't want to tell anybody. I was afraid that if my boss found out, his opinion of me would change."

In 1977, she heard of DuPont's phobia program in Bethesda. She was one of his first patients. Ten weeks later Schendeler was not only driving on the Beltway, she had signed up as a phobia therapist -- accompanying other fearful drivers on the interstate.

"Now, it's no problem," she said this week.

Four months ago, a second phobia clinic, not associated with the Maryland clinic, opened. As luck would have it it's right around the Beltway in Virginia.

"My idea was to offer services to people who might not be able to drive to Bethesda," said Dr. David Charney, director of the Phobia Treatment Center in Alexandria.

The clinics define a phobia as an irrational fear of everyday experiences. The illness, which affects approximately 10 million Americans, causes the victim to experience a "panic attack" of overwhelming anxiety, similar to "standing in the middle of a six-lane highway with cars coming at you at 60 miles per hour," according to one sufferer.

After the first attack, the phobic person avoids that situation and a second level of fear arises: anticipating another attack.

Both clinics say 70 percent of their patients are victims of "agoraphobia," fear of being in or crossing open spaces. The most common sympton is fear of driving on the Beltway.

"The Beltway is the acme, the ultimate challenge in the arena of driving," said Charney. Since phobic people are by nature more susceptible to stimulation, the Beltway's zooming cars, honking trucks, off and on ramps, dips, turns and high-speed merging of lanes are "overwhelming" to them, Charney said.

Most phobias, according to DuPont, involve stimuli our nervous systems were not prepared for, technological stimuli like elevators, escalators, subways, airplanes, shopping malls and high-speed byways.

Most of the patients are women, they say, although the Beltway phobia seems to affect as many men as women: all of them suburban residents.

The clinics offer "contextual therapy" as a means of relieving the first stage of the phobia. By that, the therapist will accompany the patient to the situation that is most fearful. Jerilyn Ross, clinical director of the Bethesda program, calls it "supportive exposure." She has accompanied patients to the top of the Washington Monument, on subways, buses, elevators and airplanes and has been around the Beltway a number of times. Both clinics also teach physiological symptoms if a panic attack does occur.

"The phobic person has a fear of fear," she said. "It's a feeling they'll lost control, that they'll step on the gas and ram into another car, or cross another lane.Phobic people are generally considered to be weak and helpless. That's not the case. Most of them are bright and competent people with one thing ruining their lives."

Ross recalls the case of a Maryland man who suddenly developed a fear of crossing the Chesapeake Bay Bridge. "At first, he had his wife handcuff him to the steering wheel. That didn't work, so he eventually had her lock him inside the trunk of their car. That's the only way he could do it."

Along with the fear comes embarrassment.

In a group session at DuPont's Bethesda clinic Thursday night, one Virginia woman who had not driven a car for 10 years said she'd rather tell her friends she "had leprosy" than admit to her phobia. Another woman proudly announced that she had driven from Bethesda to Silver Spring and back on the Beltway. She received a warm round of applause.

Of course, there are perfectly healthy drivers who avoid the Beltway simply because they enjoy the scenery of back roads or have an aversion to highways in general.

"I hate to take the Beltway," said one Germantown woman, "because of the other drivers. They drive like they're crazy."

According to transportation officials, more than 100,000 cars travel on the Beltway each day, whizzing past suburban Maryland and Virginia shopping malls, town houses, garden apartments, motels, golf courses, colleges, churches, hospitals, parks, offices and other free-way-related development.

"I don't know what we'd do without the Beltway," said Glenn Lashley, local spokesman for the American Automobile Association. "It's changed our commuting habits. Instead of suburbanites driving straight into Washington, they now commute from one suburb to another. It's altered our sports and social lives. People think nothing of going from Virginia to Maryland. It really is a blessing to the community."

Lashley did say, however, that the Beltway "had its problems" -- mainly in rush hour.

"We can put a man on the moon, but we can't figure out a way of telling people it's backed up for miles."

In 1978, according to Maryland and Virginia state highway departments, there were 3,125 accidents on the Beltway. There were 24 fatal accidents, with 29 persons killed. But in comparison with similar roads, they say, the Beltway is not an unsafe highway.

Irma Greenspoon, a Chevy Chase housewife and Washington tour guide, said she refuses to drive on the Beltway but will ride in the car if someone else is driving.

"It may be psychological, you know?" said Greenspoon. "It's right in back of my house and we fought the construction of it 15 years ago."

One of DuPont's patients, Phyllis, a 51-year-old housewife from Silver Spring, spent 20 weeks in the phobia program and last week drove on the Beltway for the first time since moving here eight years ago.

"In was all right," she said. "I did pretty well. I was proud of the fact that I didn't chicken out. Now I can do it."

Now she can go to Rockville, she said. "I've been living here all those years, never going places, never joining groups. I had no social life."

Phyllis said she thought of the Beltway "as a crowded city street, with everyone going 55 miles per hour. You feel like you're going to faint."

She never told her friends because "it seems like a stupid thing. You're embarrassed."

There's only one problem. Phyllis's Beltway phobia was cured just in time for the energy crisis and the $1.50 gallon of gasoline. "Now that I can drive," she said. "I can't afford to."