Motorists who speed through Baltimore County will soon find different school zones monitored by speed cameras.

This fall, Police Chief Jim Johnson will shift the locations of three of the county's 15 speed cameras, spokeswoman Elise Armacost said Wednesday. And early next year, the county will add a new camera at Perry Hall High School.

The addition marks the first time that the county will use a law passed in February that lifts the limitation on how many cameras it could use. It would also be the first time that the county has shuffled enforcement locations since the system took effect in 2010.

Schools that will lose cameras are Sparrows Point High School, Hawthorne Elementary School and Lansdowne High School.

"The information that we have shows that the driver behavior has improved there," Armacost said. "We are not easing up on enforcement in those areas," she said. "The traditional car-based enforcement will continue there. Obviously, we do not want to see a regression."

The cameras will be moved to Middle River Middle School, Eastern Technical High School and Catonsville High School, Armacost said.

The shift surprised Craig Rankin, a spokesman for the Lansdowne Business and Professional Association and a past president of the Lansdowne Improvement Association.

Although some residents complained that the cameras installed at the community's high school were just "money-makers" for the county, he said, "Most of the folks felt comfortable with them, and I think they adapted to them."

It's hard for drivers to see the crossing guard near the school until the last minute, he said.

"There's been several close calls there, and I thought the cameras actually helped people slow down," Rankin said.

Johnson's decisions are based not only on traffic data, but also on information from residents and from police officers who patrol the areas, Armacost said.

The county's first few speed cameras went live in the spring of 2010, and more were installed throughout that year. The number of cameras in the county has been limited to 15, but the County Council voted this year to allow an unlimited number of the devices in school zones.

Johnson's analysis shows that speeding around Perry Hall High School has been "problematic," Armacost said. The county's camera contract allows for 15, Armacost said. Starting in January, a new contract with the vendor will let the county install more.

The police chief plans to add cameras at additional schools, but the number and locations have not been determined, Armacost said.

The cameras are portable, and the Police Department's plan all along was to shuffle them as needed, she said. "We anticipate, based on constant evaluation, that some of these cameras will be moved from time to time."

Officials haven't set a date for moving the cameras, Armacost said. The county plans to post details about the locations and schedules on its website.

"The goal is not to trick people," she said. "We are telling people where these cameras are because we want them to slow down."

For the first 30 days that a camera is at a new location, speeders will get a warning, rather than a citation, she said.

The cameras are activated when a driver goes 12 mph or more above the speed limit. Violators get a $40 ticket.

alisonk@baltsun.com