NY- A Bronx subway platform has become a popular spot for gay men to have anonymous casual sexual encounters, the Daily News has learned.

The Fordham Road station, four stops from the end of the D line, is even featured on a Web site as one of numerous New York locations for men seeking other men to meet.

The cruising area is at the northern end of the long southbound platform. Anything goes, largely unnoticed – except to those in the know.

The News went to the Bronx station on a steamy summer night. In 90 minutes, we witnessed one lewd act – and were propositioned twice.

“It’s a cruising area. I’ve seen a lot of sexual activity,” said a 19-year-old man wearing a lavender-and-white Yankee cap.

He arrived with four other young men who sauntered into the station about 11:45 p.m., calling out, “Where are the cuties?” – and making comments and offers to other men that can’t be printed here.

The NYPD is aware of the Fordham Road station activity – increasing the police presence there about six months ago after some complaints, officials said.

Just last Thursday, police arrested two men for public lewdness at 1:25 a.m.

Deputy Inspector Michael Coan said there was no evidence of prostitution and said the problem seemed to abate.

“This is a condition that comes and goes,” Coan said. “We keep an eye on it, and if we get complaints about the condition … [we] address it.”

Transit officials could not recall another example of the subways being used for sex; a well-publicized three-way tryst on the Long Island Rail Road in 2002 resulted in guilty pleas by the participants – a husband and wife and his brother.

But the activity at Fordham Road is more than a public lewdness issue; in this era of AIDS, casual sex can kill.

In 2003, a Health Department survey showed just 45% of men used condoms when engaging in gay sex.

The spread of AIDS led city officials to close gay bathhouses and spurred a public awareness campaign about the dangers of casual sex, especially among gay men.

“Engaging in unprotected sex is a leading cause of HIV transmission among men who have sex with men,” said Lynn Schulman, communications director for Gay Men’s Health Crisis.

“GMHC also wants to caution men about responding to anonymous Internet ads, which could be used to lure people into dangerous situations,” she said.

Despite the dangers, the station was crawling with activity one Thursday night.

Several young men said they regularly go to the platform to watch and ridicule the “DL population” – referring to “down low,” a label for men who on the surface lead straight lives but have gay sex on the side. The group, which wanted to know whether a visitor was a cop, then headed downtown to go clubbing.

About half an hour later, a man in jeans and white sandals walked by. He made eye contact, then exposed himself.

The man, about 40, spoke very little English.

“Qué quieres?” he was asked. “What do you want?”

He made a lewd request that was promptly refused.

Subway sex shocked transit riders – even longtime ones like Gene Russianoff of the Straphangers Campaign.

“That’s a new one on me,” he said. “I never heard or thought of a subway station or subway platform as a secluded part of a park or a singles bar. If you want to go unobserved, I wouldn’t pick a subway station.”

The Web site tells readers where police hide and suggests bringing a “spotter” to look for cops or nosy riders.

It also gives the best hours to go, describes the type of men that can be encountered and features graphic descriptions of personal experiences there.

“Been in the station recently and found luck even at 3:30 p.m.,” one poster wrote. “This station is bumping again.”