Obviously, "eight million stories in the naked city" always was an underestimate. There had to be more than that. Only six of those stories are told tonight in a new public TV documentary, but this scratching of the surface has thrusts that go very, very deep.

"Third avenue: Only the Strong Survive," by Jon Alpert and Keiko Tsuno, is the second of this season's "Non-Fiction Television" programs from New York's Channel 13. While it is a program with dozens of apparent flaws, it still emerges in the end, paradoxically perhaps, a total success. The one-hour tape will be shown at 10 on Channel 26.

Third Avenue, a prologue says, runs 16 miles through New York City, from Brooklyn through Manhattan to the Bronx. It links a number of ethnic and socioeconomic groups and from these the procedures found six families who are presented through real-life vignettes full of energy and insight.

How much reality has been dabbled with in order to produce remarkable footage is not clear; it is confessed at one point that a car theft captured on tape was in fact "a reenactment." But then we see one of the perpetrators go into jail and sit on his cot, and this sure is real enough.

New York is a place where people can still live lives of shameless banality, and yet as presented here, the subjects of "Third Avenue" are enormously affecting and genuine. Their stories are so overwrought with poignancy and pathos that they could put a hundred playwrights out of business. p

A combination of technological factors -- including the greatly increased portability of videotape equipment -- and a trend in television away from fabricated fantasies and toward informational entertainment, suggests that vignettes like those in "Third Avenue" may literally put dramatists out of business in the decade ahead. Manipulated reality is going to make the "well-made play" obsolete -- at least on TV, and TV's what counts.

The second episode on the program deals with a Bowery bum named Joe. He frequents a dive that seems worthy of Eugene O'Neill; it's Harry Hope's plae come to life and imitating art. Later, a brief driving tour of 42nd Street, where young boys say they're looking for easy money doled out by "homos," outdoes artificial visions of urban demoralization like "Taxi Driver" and "Hardcore." It almost makes them look ridiculous.

The first episode deals with Sonny and Eddie, who operate a Brooklyn auto salvage business that is not, shall we say, entirely on the up-and-up. I'm the type of person who always wants more," says Eddie; two months later we join him in jail on a car theft charge.

It's the little crooks who get caught and the big ones who get glorified, Eddie complains. "The only reason I don't rob a million dollars is 'cause I never found out where they keep a million dollars," he says.

Joe of the Bowery is asked by a bartender, "How come you drink so much?" He replies with chipper flippancy, "I'm an alcoholic," as if he were saying, "I'm a Presbyterian." Later, to his wife, he makes the pledge heard 'round the world; he will stop drinking "tomorrow" and, swigging a beer, "today's the last day."

A welfare mother named Trudy lives on 183rd street in the Bronx behind a door on which is incongruously posted a picture of C3PO and R2-D2 from "Star Wars." Her five children cry, she weeps herself when she cradles one in her arms, and she says she must carry water up from downstairs because hoodlums stole the pipes out of the building.

Ricky inhabits the ethereal carnival of 53rd and Third, known as a mecca for young male prostitutes renting themselves to other men. Ricky says he takes 60 to 70 pills a week, makes a minimum of $30 per customer, and adds, smiling, "For some reason, I meet an incredible amount of lawyers."

Raul Lopex lives in Brooklyn, tries to spread words of biblical hope on streetcorners, and appears unaware that several of his seven children have compeltely and dramatically forsaken the values he imagines himself to be preserving. A daughter is a prostitute. A son sells dope. A friend of Raul's explains, "It's the devil's fault."

Most of these portraits are at least vaguely despairing and conductive to dismay, so it is only fair that the last, the Pascone family of 11th Street in Brooklyn, has a peculiar but very moving affirmation.

Mr. Pascone's little-patronized barbershop emerges as an embattled bastion against time; to a complaining customer in the barber chair he says, "Keep still. I know what I'm doing."

Never far away is the light of his life and of this program, Mrs. Pascone, whose meatball-rolling is an art form, who would have "another dozen" children if nature would let her, who wants to be taken to a restaurant for filet mignon on her next birthday, who agonizes over the inflated cost of cooking oil, and who for 17 years has played bingo and never won once.

The family, reunited for a gathering holds hands and sings "I Can't Smile Without You" along with a record. There is talk of selling the house and abandoning Third Avenue, but Mrs. Pascone breaks down crying. She cannot bear the thought of leaving this glorious hell-on-earth.

The final shot of the program, after the closing credits, finds the family assembled for a video snapshot in front of the barbershop. The portrait is a naive masterpiece. It could stay on the screen for five minutes and one could still find things to savor in it.

But the program is unfortunately rush-hour all the way through. The producers shot too much tape, and tried to squeeze in too many scenes. Some things fly by before they have a chance to register. And yet there is more drama, more life, more love and passion in this short hour than in a week's worth of prime-time potboiling.

"Third Avenue" is a triumph of its kind and a guidepost to a new age of television. It is less a forced attempt at microcosmic commentary than a reminder that whenever time marches on, it always tramples people in the process. This program is essentially about whatever it is that makes people stand up and curse and dare anybody to trample them again.