It sounds like a plot from Sanford and Son.

Two young guys named Jones and Artis are driving a sick pickup truck into National Airport. In the back is a little cement and a little equipment. In their pockets is a contract to rebuild a curb in the VIP parking lot.

The job costs less than $1,000. The profit for the two young men is less than $100. But you have to start somewhere in the construction business.

Carl D. jones and James Artis have done better since that day than the bumbling Sanfords could ever hope.

Theirs is now a $4.5 million a year construction and excavation business. It has 240 exployees most of the year, spacious offices at 1112 11th St. NW., an average of eight major projects at any one time and the reputation to be able to land seven-figure jobs routinely.

If your sidewalks were repaved during 1976 and you live in the District, Jones and Srtis did it. If you have frolicked in the Shaw Playground at 8th and S Streets NW., Jones and Artis built it. If you live in Far Southeast, you probably have Jones and Artis sewers. If you have noticed the park at Metro's Judiciary Square station . . . three guesses.

But the Jones and Artis COnstruction Co. is in trouble every day. Carl Jones, the president, confesses it. "There's a hooker in every job we do," he says. "One mistake, one bad thing, that could be it."

The immediate reasone is that Jones and Artis, and every construction company of similar size, is vulnerable to variables: bad weather, fire, theft, accidents.

The overriding reason is that, as Jones put it, "highway work in this city is nonexistent." There is one large, flowering money tree herebouts: the subway. But most of its construction contracts went to huge companies, in $100 million packages. That leaves the Joneses and Artises in the position of having to jockey for subcontracts.And that can make success a matter of who you know.

"We have a good working relationship with the big contractors," Jones said. "But friendship only goes so far. The big guy still has to make money when he subcontracts to you, and if he isn't going to make money, he isn't going to do it."

Jones and Artis are aware, however, that whites often subcontract work to all-black companies like theirs to meet government equal opportunity guidelines. The racial makeup of Jones and Artis "has helped," Jones said.

One convincing piece of evidence is that, a year ago, Jones and Artis became the first minority subcontractor for Metro. The company also gets what Jones called a "substantial" amount of "8A jobs" - government work earmarked by the Small Business Administration for minority-owned companies. The gross from such work added up to $3.83 million in 1975, enough to rank Jones and Artis the 58th largest black-owned business in the nation.

What has also helped is the backgrounds of Jones and Artis themselves.

Both grew up in small southern towns. Both hold engineering degrees from Howard University. Both had government careers that taught them the construction business from the "other side" - Jones as an engineer for the Redevelopment Land Agency and administrator for the Department of Transportation, Artis as a bridge inspector for the D.C. Department of Highways and Traffic.

So they are a little more secure than many private entrepreneurs in Washington. "If things really went bad," said Jones, 36, "we could always go back and get a job on the Metro or in the government somewhere."

They are not at that point yet, even though 1976 was a strange year. The company's gross was its highest, but its profit margin was its lowest. "People are cautious, nervous and anxious," Jones said. "These aren't normal times, but what's normal times?"

One candidate might have been 1972, when the company started. "That was a time when you could hardly miss." Jones said.

Indeed, after their debut at National Airport, Jones and Artis quickly won three more small jobs, including a $1,300 repaving and landscaping contract at Georgetown University. "That was the first time we went out to dinner to celebrate," Jones recalled.

In the early years, the company did a great deal of "private" work - drive - ways, subcontracting for housing developers, small repaving jobs. It is now out of the field. "We didn't make anything to amount to anything," Jones explained. "Construction has always been a flash-in-the-pan business, and when the housing squeeze started, we saw we couldn't rely on private work."

The company hopes, in fact, to rely on no one thing in particular.

It has now done six Metro jobs, but the work was different each time - construction of a park, repaving of I Street downtown, patching around an airshaft, boring a tunnel at a river crossing in Southwest. It did a $2.9 million sewer job in Northeast last year, but it also repaved a Northwest stret for one-tenth of that.

The company hopes to expand, Jones said, into major highway work. But because of opposition to father freeway construction in the area, Jones acknowledged that that may prove difficult.

"The I-95 thing cut off a lot of work tha twould have come our way," he said. As a hedge, the company is preparing to bid on roadwork in Atlanta and Baltimore, he said.

"The thing is not to overextend yourself, though," said Jones, who still speaks with a Demopolis, Ala, accent. His company does not necessarily do jobs better, Jones said, "but we've gotten the spillover from the big pond only the big fish can swim in."