D.C. police, waging a new offensive against prostitution, have turned the normally bustling 14th Street strip at Thomas Circle into a virtual obstacle course for late-night drivers, with roadblocks cutting off access and officers strictly enforcing minor traffic and pedestrian regulations.

The goal, according to Capt. Mike Canfield, is to inconvenience prostitutes and their customers and to move their activity from the residential and hotel area near Logan and Thomas Circles to the business district near K and L streets.

The action by police comes as the warm weather months arrive, a time when street prostitution in the area traditionally increases. Prostitutes wave and beckon as customers cruise past in cars, often creating late-night traffic jams. Area residents and police have waged an ongoing war against the phenomenon, with the barricades being the tactic of the moment.

Police say the roadblocks have resulted in nearly empty streets and some confused drivers, but apparently have cut down the prostitution business in the area. The operation, according to police, resulted in 221 arrests in May for various offenses and brought about a 30 percent drop in street crime.

Most nights since early May, officers have set up wooden sawhorse roadblocks on several corners along 14th and 15th streets between Thomas Circle and Q Street NW. The roadblocks are usually in place between midnight and 4 a.m., and their location is often changed from night to night.

Persons who have a legitimate reason for entering a block are allowed to do so, officers said, but those who try to slip by the sawhorses are likely to be chased by a police car. From time to time, patrol cars have cruised through the area, issuing tickets to drivers of double-parked cars and ticketing or picking up women who jaywalk through the area and who cannot produce identification.

"It's much more cost-effective to enforce minor crimes instead of solicitation," said Canfield. Setting up wooden barricades and enforcing minor laws, he added, takes much less time and manpower than using undercover officers who must testify in court after they have arrested a prostitute for soliciting.

A similar tactic was used successfully last summer to battle prostitution in the area around McPherson Square, according to police. In recent months officers also have used roadblocks to disrupt drug traffic on upper 14th Street. That project will be resumed later this summer.

Canfield said there is no way to completely rid the city of prostitutes, but he hopes that within the next few weeks, the barricades will encourage the women to move. Last week he said he and his officers personally made the rounds on the streets and talked directly to the pimps. "We told them that it would be to their economic advantage to move the girls south of Thomas Circle," Canfield said.

The roadblock program was briefly suspended last week after police received a number of complaints from persons inconvenienced by the blocked streets. However, several officers said there were also citizen complaints when the roadblocks were removed, and the project has been resumed. Deputy Police Chief Rodwell Catoe has promised to launch a public relations campaign to inform residents of what is going on and why.

Many residents already seem satisfied with the program.

One recent evening, a young businessman trying to get to his home on Rhode Island Avenue stopped near Thomas Circle to talk with a reporter. The roadblocks are "a little inconvenient," he said, but added: "I have seen a reduction in prostitution traffic ."

Farther up the street, Gregroy Macklin, 39, maneuvered his bicycle through a barricade and stopped to watch police officers arguing with occupants in a car that had tried to pass through. "Everybody I've spoken to is in favor of this," said Macklin, who lives on nearby Kingman Place.

He said "shoppers" apparently looking for prostitutes drive though his street as they circle 14th, P and Q streets. "Sometimes that one-block street Kingman looks like a highway," he added, shaking his head.

"People feel safer and the street looks nicer. . . . It will help bring business for sure," said Syed Ali, the night manager of the Holiday Inn just south of Thomas Circle. Ali said tourists with families "don't want to come see ladies like that."

While the citizens in the area might be happy about the roadblocks, the prostitutes are openly annoyed. One woman who called herself Michelle complained that the program has hurt business. "Now we have to work during the day," she said, rolling her eyes.

When an officer suggested that she ply her trade south of Thomas Circle, she looked in disbelief, pointed to a wooden barricade and asked, "Then will the joke be over?"

Another woman who called herself Judy acknowledged that she has been a prostitute for some 17 years. She said she moved to Washington from Las Vegas eight months ago, and that she had been accustomed to making $300 to $400 a night here.

"Now it's down to not knowing if you're going to go home with anything." She looked wistfully at the empty intersection of 14th and P streets. "You'd think by now the guys would have the sense to park and walk to get a girl."