To catch drivers who run red lights, police usually have to run red lights themselves, risking an accident. Minneapolis tried to fix that by using cameras to record the licenses of drivers who ran lights, but courts ruled the system was illegal.

Now Bloomington is investigating the use of "white light enforcement technology," a system used by police in Texas and Florida to catch red-light runners using just a single police officer. Bloomington officials believe that if the city decides to install the technology, it would be the first in Minnesota to do so.

The system uses an indicator light visible to police waiting in a driveway or cross-street near an intersection. The indicator lights up at the same time as the red traffic light facing the other direction, allowing police to see whether a vehicle goes through an intersection after the light has changed.

White light technology was pioneered in the 1990s in Richardson, Texas, a suburb of Dallas. Police there still use it.

"It works real well for our guys, and it's a whole lot safer than having to bust the light," said Sgt. Kevin Perlich, public information officer for Richardson police. "It's a good thing all round -- safer for us and safer for the public."

Nationally, 40 to 45 percent of all crashes occur at or near intersections, and crashes caused by drivers who ran red lights killed 805 people in 2005, according to the National Highway Traffic Safety Administration.

Bloomington has not committed to using the system. First, the city needs to figure out how to make the technology work with its traffic signals. Using a $10,000 grant from Intelligent Transportation Systems Minnesota, a nonprofit group that promotes innovative transportation technology, the city plans to hire a consultant to work out the mechanics. The City Council then would make a decision on whether to install the technology, said Chad Smith, Bloomington traffic and transportation engineer.

"It's not as simple as just hooking up another light," he said. "The issue is how to hook it into the control system for a traffic signal without overwhelming the other equipment, like a piece of equipment that ... makes sure a red light isn't burned out."

If the system is used in Bloomington, where the penalty for running a red light is $125, it likely would be a color other than white, Smith said. The Texas system uses a white light attached to the back of the traffic signal head or a signal cross beam. But Smith said any new lights in Bloomington would have to avoid looking like the small white lights installed on some Minnesota traffic signals that blink or shine when an emergency vehicle is approaching to override a traffic light.

One choice would be blue lights, Smith said.

"Our hope would be that ultimately we'd reduce the number of red-light runners and crashes," he said. "Our goal isn't to write a lot of tickets."

Perlich said that in his Texas suburb, white-light enforcement is used at dozens of intersections "because it's really inexpensive and easy to put in." In the late 1990s, the cost was estimated at about $500 per intersection. The biggest burden associated with the system is making sure light bulbs get changed regularly because they burn out with constant use, Perlich said.

They've had a few complaints from residents about using "big brother" tactics, Perlich said, but the department views the technology as an effective and economical traffic enforcement tool. Before, Perlich said, at least two police officers had to work an intersection, with one alerting the other that a violator had just driven through. Now, he said, officers on motorcycles or in discretely parked patrol cars can handle the job single-handed.

"It's just boom, boom, go get a violator," he said. "They see us out there, so we're not trying to ambush them."

Mary Jane Smetanka • 612-673-7380