The D.C. police department announced yesterday that it has requested that 2,400 speeding tickets issued in October be dismissed and that motorists who have already paid their fines be reimbursed.

On an otherwise routine day last month, two teams of police officers, one in Northwest Washington and the other on East Capitol Street, set out to snare speeders. They surveyed the areas and pointed their high-tech photo radar vehicles toward oncoming traffic.

But there was one problem: The tickets were not issued based on the actual speed limits.

Instead, the citations were assessed for limits that were five miles an hour below the legally acceptable driving speeds on those roads.

"It was an error, and we intend to correct it," said Sgt. Joe Gentile, a police spokesman. "This is why we do periodic [audit] checks. That's how we caught it."

The District's photo enforcement traffic program, which also includes cameras that capture the license plates of red-light runners, has been controversial since its inception. Advocates say the cameras have made the streets safer, are cost-effective and are better at catching violators than dangerous police chases are.

But critics argue that the cameras are an invasion of privacy, do not always work properly and are used to enhance the city's coffers, not deter reckless motorists.

In the case of the speeding tickets issued last month, however, the problems had more to do with human error than electronic malfunctions.

Some city leaders were disturbed by the errors.

"Clearly they shouldn't make this mistake," said D.C. Council member Kathy Patterson (D-Ward 3), who otherwise supports the traffic cameras. "The speed limit on any street is easily knowable. I think when District agencies make mistakes, they need to correct them, and it sounds like that's what they're doing."

According to the police announcement, the erroneous tickets were issued Oct. 15 in the 3300 block of East Capitol Street and Oct. 15, 17 and 19 in the 2500 block of Porter Street NW.

At the first location, the photo radar vehicle cited 2,000 motorists based on the proper speed limit of 40 miles an hour. However, when the tickets were processed at Affiliated Computer Services -- the Dallas-based company that handles radar-enforced speeding tickets for the District -- a clerk mistakenly entered a speed limit of 35 miles an hour, meaning motorists were assessed higher fines.

Maury Hannigan, head of ACS's District office, said yesterday that he did not know how the error happened. But, he added, "the fact remains that the system caught the error, and I'm pleased with that."

At the second location, officers scouted the site in advance and noticed that the speed limit was 25 miles an hour. However, when they arrived several days later to set up their radar equipment, the limit had been raised to 30 miles an hour, and the officers accidentally based the radar on the older limit, police said yesterday.

"It was a mistake on the part of the officers that should have been checked when they set up," Gentile said.

Police Chief Charles H. Ramsey made the request to dismiss the tickets in a pair of letters to the Bureau of Traffic Adjudication.

The approximately 73 people who have already paid their fines will be reimbursed, Gentile said, adding that ACS will send a letter to all motorists who received a speeding ticket from either location on the days in question.

The city issues approximately 30,000 speeding tickets a month, both through photo radar and sightings by officers, Gentile said.

Motorists who believe they received erroneous tickets at either of the locations should call 202-756-5884.