By DOUGLAS MARTIN

Come midnight, Eighth Avenue in midtown is a street of neon thrills, lurking dangers and impossible expectation, a Felliniesque montage where a group of giggling theatergoers crowds into a peep booth to have something to talk about on the ride home.

But there is pain in the face of the old man jiggling two quarters in a paper cup, and an odd frenzy in the voice of a man passing out handbills for a topless bar. Doris Brown, a 41-year-old prostitute looking for business across from the Port Authority Bus Terminal recently, said life wasn't getting any easier.

"There's money out here, but some nights it takes so long to get it," she said.

Except for the part near Eighth Avenue, 42d Street is now largely a surreal ghost town awaiting a new life. It is Eighth Avenue itself that has become the most sex-saturated street in the city, the police, business people and leaders of community groups said. In the last five years, sex shops and adult theaters have tripled to 15 from 40th to 48th Street, and the corridor south to Penn Station is peppered with about a half dozen more. In addition, many stores are situated on side streets just around the corner from Eighth Avenue.

Although crime statistics are not broken down by street, the police believe the crime rate is the highest in the Times Square area.

This is the avenue that seems never to improve, even as Broadway and Seventh Avenue to the east have taken on a new sparkle, and the Clinton neighborhood immediately to the west more or less succeeds in burying its Hell's Kitchen past. " Eighth Avenue is like the same jungle it was I don't know how many years ago," said a businessman running for a late bus. "It just swallows people up."

Gerald Schoenfeld, chairman of the Shubert Organization, fears the street's continuing blight threatens the revitalized theater district. "It is a street people try to avoid," he said.

But there are gathering whisps of change. Several weeks ago, the state Urban Development Corporation took title to all of the east side of Eighth Avenue between 42d Street and 43d Street to build a hotel as part of its redevelopment project; Disney is among the bidders. The businesses there now include peep shows, video shops and adult book stores. The condemnation process is expected to start soon.

William H. Daly, director of the Mayor's Office of Midtown Enforcement, said that, in terms of square footage, this one step will eliminate nearly 30 percent of sex businesses on Eighth Avenue between 40th and 53d streets. Even more important, Mayor Rudolph W. Giuliani is pushing for a yearlong moratorium on the opening of sex businesses in the city. During that period, zoning changes would be formulated to push the sex shops to the city's industrial periphery. Current shops would likely be allowed to recover at least some of their investment before having to move, although details have not been determined.

Last week, the City Planning Commission approved the moratorium. It next has to go the the City Council, and the city Planning Department is drafting zoning regulations.

Although the rules will apply equally to sex shops from the Bronx to Staten Island, perhaps its greatest impact will be felt on Eighth Avenue. "The initiative is generic and citywide, but would certainly change Eighth Avenue," said Andrew Lynn, executive director of the Planning Commission.

For the Times Square Business Improvement District, which is now focusing on Eighth Avenue, such action is crucial to stemming the street's slide. "We absolutely need government intervention," said Gretchen Dykstra, president of the group.

According to a recent study by her group, there is economic incentive for landlords to rent to owners of sex shops. The study found that rents from 40th Street to 53d Street for sex businesses range from $90 to $125 per square foot per year. Rents for nonpornographic uses along Eighth Avenue are $40 to $50 a square foot north of 48th Street and $50 to $80 south of it. Still, the study found, there's money to be made on the avenue: average rent for nonpornographic uses elsewhere in western Manhattan was $35.

The study also found a lower commercial vacancy rate than for the city as a whole -- 9.6 percent, compared with 15 percent citywide -- a figure that attests to the strong commercial interest in the area. " Eighth Avenue could become a far more vibrant retail strip, " the report declared.

There is some evidence this is already happening. Ben & Jerry's Ice Cream says the company's store at the northeast corner of 43d Street is one of its highest-volume sellers. Partly as a result, Green Mountain Coffee said it is planning to open an upscale coffee bar next door. Between 46th and 47th Streets, bright new awnings outside bustling establishments indicate a new retail energy.

The once-grubby Port Authority Bus Terminal, at Eighth Avenue and 42d Street, bristles with new upscale fast-food outlets and, after years of trying, the Port Authority finally convinced a bank to install automated teller machines earlier this year. It quickly became one of the city's busiest A.T.M. centers.

Worldwide Plaza, the five-year-old complex between 49th and 50th Streets, has no vacancies for either commercial or residential space.

As a result, real-estate executives and property owners voice much optimism about the avenue's future. " Eighth Avenue is going to have a fantastic decade," said Arthur Zeckendorf, whose family built Worldwide Plaza and is scouting for other opportunities on the street.

But it is premature to say any corners have been turned. The street still has a dangerous edge, and considerable low-level drug dealing continues, despite beefed-up police efforts.

"There are about 30 junkies on the corner every morning when I walk my dog," said the Rev. Dale D. Hansen, pastor of St. Luke's Lutheran Church on 46th Street, just around the southwest corner of Eighth Avenue.

But things are still better than they used to be, neighborhood people say. Child pornography, a staple of the old 42d Street a decade ago, is seldom seen on Eighth Avenue, the managers of the video stores say. And the dozens of massage parlors, more dens of violence than sex, were chased from Eighth Avenue in the early 1980's. "This was a meaner street back then," said Mr. Daly, of the midtown enforcement office.

A backhanded compliment comes from Ernest Schroeder, who runs the Full Moon bar at 46th Street. "They've eliminated the low-lifes up and down the street," he growled. "Those were my customers."

The sex shop business has changed, too. Mr. Daly says that organized crime's hold on pornography has been loosened, largely, he said, because of aggressive Federal prosecutions. Smaller entrepreneurs, many from India or Pakistan, have taken over, he said. With little capital, they tend not to offer live entertainment, but pirated, often crudely reproduced videos at $5 each or three for $12.

"There are too many video stores, and all of us hurt each other," said a worker at XXX Video at 778 Eighth Avenue. "It is a bad sign."

Rick Travis, owner of the Pleasure Palace at 733 Eighth Avenue, said that he voted for Mr. Giuliani and would do so again, but that the Mayor was wrong in trying to control sex establishments. "We pay millions of dollars in taxes and give jobs to a lot of people who normally would otherwise be unemployed," he said.

He also contended that sex shops were a benefit to property owners. The Oriental gift shop that preceded him in his space did not generate enough business to pay the rent, he said, whereas he is prompt with his.

"My landlady wanted somebody who could pay the rent," he said. "It doesn't make her a porn queen. It makes her a businessperson."

Even so, there are property owners who are declining to rent to pornographers. Reasons vary from moral considerations to concern that the value of upper floors will be lowered by renting to an objectionable tenant on the ground floor.

"We want to upgrade our property, not downgrade it," said Richard Barth, vice president of corporate properties for Chemical Bank. He said he has passed up many opportunities to get high rents from pornographers for the bank's property on the northwest corner of 43d Street.

Robert Cohen, a developer who just bought four buildings, including the defunct Covenant House social service agency between 43d and 44th streets, said he would never rent to a sex shop, despite the "crazy numbers" he said he has been offered. "You end up cannibalizing the value of your investment," he said.

Peer pressure is also a factor. Carvel Moore, executive director of the Fashion Center Business Improvement District, which includes Eighth Avenue from 35th to 41st Streets, says more than 80 percent of the landlords there have signed agreements not to rent to sex shops.

Among them is Mark Orbach, whose commercial space at 585 Eighth Avenue was vacant for almost a year. He heard generous offers from sex merchants, but owners of neighboring buildings begged him not to accept them. They even enlisted his rabbi to lobby him.

The result was that Mr. Orbach rented his space to a clothing store for 60 percent of what he could have taken in from a pornographer; his neighbors gave him money to help him make up for the loss. "I would like to clean up Eighth Avenue," he explained.

Copyright 1994 The New York Times Company