The Prince George's County Police Department is pushing a bill that would add cameras to the outside of school buses to nab drivers who disregard the buses' flashing red stop signs.

That violation, which police say can endanger students being picked up or dropped off, was reported 748 times by 376 county bus drivers in 2011, according to Police Major Robert Liberati, who drafted the bill and submitted it to the County Council.

"We're doing this as a preventative measure," Liberati said. "The idea here is not as much on the individual violations as it is on presenting a public safety message that when you're near a school bus and the lights are activated, you must use caution and stop."

The school bus cameras act like red-light and speed cameras already in operation around the county, Liberati said. Each one would take two photographs of cars that illegally pass school buses, including one of the rear license plate that police can use to track violators.

The county already accepted bids for the 20 cameras, though those bids would be thrown out if the council votes down the bill. Since the vendor would be able to keep part of the revenue from the $150 traffic tickets that would result, the county wouldn't pay anything for the cameras, Liberati said. The contract includes the option to add more cameras if the county deems the program a success.

The bill comes after a 2011 state law that allows counties to add school bus traffic cameras, but requires local legislation to do so. Since then, Frederick, Montgomery, Washington and Charles counties have begun tacking cameras onto their buses.

"This is a pilot for us," Liberati said. "It's just one part of our traffic safety program."

Prince George's County had 25 red-light cameras at the end of last year, and is adding nearly 50 intermittently in 2013. The county issued about 39,500 red-light violations in 2012, and has brought in about $8 million since the first cameras were installed in September 2011.