Her name is Fay Shannon, and she rises every morning before dawn and loads 200 sandwiches onto her truck, as well as an American smorgasbord of Twinkies and Cheetos, Snickers and M&Ms, cold Pepsi bedded in ice.

About her personal life, she reveals little, except that she is 38 and lives in Prince William County with four dogs, truck payments and a mortgage. She used to sell birds and fish at a pet store.

If asked what she does for a living now, she'll say that she has finally found a job she loves. For the last three years, she has driven the traffic-clogged highways of Tysons Corner, dispensing snacks and lunches from "my roach coach."

A roach coach is actually a food service truck, but neither the drivers nor the customers address it by its formal name. And when Shannon speaks of hers, it's happily, with affection -- as in, "You ought to taste what a fine cup of coffee my roach coach can make," or, "Today, this old roach coach is pretty much breezing along."

There are fewer than a dozen such vehicles operating in the Tysons area. Fay's is a white Ford, with stacks of extra paper cups on the driver's seat, two pairs of dusty sunglasses on the dashboard, and a sign -- "Tom's Chuck Wagon" -- on the door.

Fay stocks it each day with about 200 pounds of ice from a Merrifield supplier; when the ice melts, it drains out the back, leaving small puddles in red-dirt construction sites where she has been, or wet trails in alleys behind auto body shops.

With a shiny change-maker hanging from her jeans belt, and a rusty fold-out table as her counter, she computes in her head the net worth of:

*Labor foreman Paul Owens' breakfast of one steak sandwich, one sausage sandwich, one Mountain Dew, one Tropicana Chugger and one box of Copenhagen snuff -- $4.50.

*Drywall hanger Michael Hunter's breakfast of one bologna sandwich, one Coca-Cola, one Mountain Dew -- $2.15.

*Carpenter Terry Barton's breakfast of coffee and pizza -- $1.25.

And wherever she goes -- no matter how many times she sponges up coffee spills or digs soda bottles deeper into the ice to keep them cold -- she's followed by the inevitable roach-coach jokes:

*"Is this stuff fit for consumption today?"

*"I'm a glutton for punishment -- I'll take the bologna."

*"Hey, sweetheart -- how thick's the coffee today?"

But her truck is county-inspected a minimum of every 120 days, the food either factory- or restaurant-packed, and the wisecracks a measure of affection for the shy woman who brings drinks to the thirsty, food to the hungry.

'Fay's great," said Kenneth Rexroad, 37, a painter, "and that's why we have to give her a hard time."

"It's only because I like her," agreed Tyrone Hunter, 28, of Hurley's Auto Radio.

The only product Fay ever remembers getting complaints about was "Creme Flips," a folded-over cake with 1 1/2 inches of vanilla-flavored filling. "I thought I had stocked 'Banana Flips' instead."

She routinely puts in 10- or 11-hour days, depends upon commissions for her earnings (Tom Flanagan, her boss and the name on the truck, estimates the average driver makes $12,000 to $14,000 per year) and gets no tips.

But, she says, the job is fun.

"I like pretty much everything about it. You're on your own. You're not tied to a desk or anything. Less than 1 percent of the people aren't nice, and they don't really mean it -- probably they just had a bad day."

All that driving around has stimulated her interest in architecture and construction. "It's really interesting to see them go up from a mud hole in the ground," she says.

And because of the many foreign workers in the area, she has learned the rudiments of Spanish. "I tried with Vietnamese, but, whew, that's a tough one," she said.

If she has a concern, it's the roach coach competition, which she describes as "stiff" -- despite a Tysons boom, with an estimated 2.5 million square feet of office space under construction. There are no turf rules; it's first come, first served. And site superintendents willing to grant "exclusive" rights to one truck have been known to switch if somebody else promises quicker, better service.

And lately, Fay says, there's been something of a food-truck explosion. "Every other roach coach I see at Tysons is brand new," she sighed. "Really -- I see a new one out here every . . . wait . . . here comes one now."