In July 2013, Lawrence police and Kansas University researchers began a traffic safety experiment at two Lawrence intersections.

They installed blue lights at 23rd and Iowa and 23rd and Louisiana streets. The blue lights, an addition to the existing red, green and yellow, were designed to help police see and catch red-light runners. The goal was to change the behavior of drivers over time.

The findings are in, and the lights do seem to have had some effect on red-light running at the intersections.

The university studied the lights for three months and found a 42 percent reduction in red-light running for left turns at the two intersections, said Steven Schrock, an associate professor in KU’s Department of Civil, Environmental and Architectural Engineering.

“Before everything started we had about 11 instances of red light running for every 10,000 vehicles entering the intersection, in the morning,” Schrock said. “In the evening, it jumped to 21 per 10,000 entering vehicles.”

Three months after the blue traffic lights were installed, the numbers had dropped from 11 to five per 10,000 vehicles in the morning and from 21 to 16 in the evening, Schrock said.

At a typical intersection, an officer has to be facing the traffic signal to see when it turns red and catch a light runner. The blue light is visible from all directions and turns on when the traffic light turns red, allowing police to see from any direction whether a driver made it through on yellow or blew the red light long after it turned.

Lawrence Police Department spokesman Sgt. Trent McKinley said there were some benefits to the officers having the lights in place, but a few problems were also found.

McKinley said a benefit was that the lights give officers flexibility as to where they position themselves to observe violators and sometimes provide a safer location to enter traffic and stop a violator.

“One problem we found with those installed on the two test intersections was the blue light was not situated in the highest point above the signal in question,” McKinley said. “Thus, officers were not able to have a full 360-degree view of the blue light, which provided to be a limitation.”

The blue traffic lights remain in place at 23rd and Louisiana streets, but no longer at 23rd and Iowa streets. Schrock said that after that intersection was rebuilt this year, the geometry of the intersection has vastly changed and he doesn’t think the blue lights will be reinstalled.

Schrock said he thinks there is an advantage to using the blue traffic lights.

“For something like this you think of it as a tool in the tool box as things to reduce red-light running or safety at intersections in general,” Schrock said. “So like any tool there is the right time and place to use it.”

The university sent its findings to the Mid-America Transportation Center at the University of Nebraska and to Lawrence Traffic Engineer David Woosley at the end of November. The transportation center has plans to publish the report on its website.