The man sat in his car parked on the side of the highway, his fingers flitting across a 12-key counting board at a speed of more than 5,000 clicks per hour.

"This is 'bout like playing a piano," said 63-year-old Edwin King, a retired electronics Technician. "The music is out there," he said, motioning to the congested highway. "But the keys are inside the car with me." A former saxophone and clarinet player, King is one of six retired men who sit beside Northern Virginia highways for 12 hours at a time -- counting cars.

The tedious task pays a maximum of $3.55 an hour, but this is one job a machine can't handle.

The human car-counters "help us to determine traffic flow data," said Virginia Department of Highways and Transportation spokesman David Gehr. "Whether a section of highway needs widening, where stoplights should be placed on state rorads to keep the traffic moving. It even helps us determine what types of road surfaces wear best."

Sitting in cars parked on the shoulders of Shirley Highway near the Potomac River, King and three other traffic counters recently monitored the most heavily-traveled road in Virginia.

Approximately 93,000 vehicles zoom past there 12 hours, a dizzying pace for the human eye.

"One man couldn't count for 12 hours," King said. "The counts are worthless unless we get every car, and you start seeing things if you work more than an hour at a time."

King flicks off from 2,000 to more than 5,000 vehicles per hour. "This is ideal for a retired man," he said. "If my wife and I sat together all day we'd likely kill each other."

But life off the emergency lane has its spine-tingling moments.

King's foreman, Clint Canfield, said he remembers counting cars near the northbound King Street exit on Shirley Highway last December.

"I looked back when I heard the sound of a collision and here was this damned car doing somersaults and heading right for us," Canfield said. "Luckily it stopped flipping over before it reached us . . . scared me half to death."

Another counter stopped taking naps during his breaks after a semitrailer, loaded down with portable toilets, hit a bump and lost part of its cargo.

"He awaked to find a 'Tidy Toilet' resting on the hood of his car," Canfield said. "It was a bit hard to take."

At 80 counting areas throughout Arlington and Fairfax County selected by the highway department, two pairs of counters work both directions of traffic. Each team member is on one hour, off the next.

The 12-key counting boards are divided into several sections, with five top keys to record Virginia vehicles. The lower keys record out of state vehicles and buses. The counters must also pick out pick-ups, panel and two- or three-axle trucks.

King, who enjoys the fresh air, said he couldn't think of a better way to earn his living.

"But it wouldn't pay for a youngster to get involved in this job," he said. "It doesn't pay much and there's no insurance or other benefits."

King's partner, 63-year-old Bill Stickley said traffic counting was the only job he could find.

Stickly grimaced while jets from National Airport roared overhead.

"Dagnabbing planes . . . this job is nerve racking," Stickeley groused. "And after three years, it gets pretty damn monotonous."

During the long, hot summer, Stickley said, the counters pack lunches in ice chests and tote patio parasols and lawn chairs to the job.

In winter, he said, they "keep turning on the car heaters to keep from freezing to death.

Another disadvantage, the counters said, is finding rest room facilities. "In some places, we're right next to a gas station or a rest area," said foreman Canfield. "But in some places, it's the woods."

Which presented a problem for two female traffic counters, Canfield said.

"They wound up driving up and down the highway looking for a rest area," he said. "They didn't stay on the job too long. They said it was too primitive."

But retired postmaster George Mettauer, 59, likes the uncertainty of never knowing where his next counting stop will be.

"You're going to a different location every day," he said, "not wasting away in some rocker. You're out here on your own, with nobody to bug you. That's what it's all about."

Figuring out an easier way to count cars is also what it's about. Bill Stickley accidently hit on a solution when, to combat boredom, he set up a portable television set on the hood of his car.

Over the static of his CB radio, Stickley said he heard passing motorists asking each other about the "newfangled radar equipment" on his car.

Stickley smiled. "It sure slowed 'em down anyway."