BonnerSprings.com

A state traffic engineer says deadly accidents, by themselves, don't necessarily increase the chances that an intersection will get a traffic signal.

A traffic accident March 28 took the life of a Bonner Springs High School student March 28, raising questions about how the decision process for which highway interchanges get traffic signals.

Because the interchange in question - of Kansas Highways 32 and the ramp for northbound K-7 - involved two state highways, the decision to not install signals at the interchange was the Kansas Department of Transportation's to make, just as the agency had decided in favor of a traffic light at the adjacent interchange, for K-32 and the southbound K-7 ramp.

"We look at the pure number of crashes per year," said Kristy Rizek, a traffic engineer at KDOT.

That is, fatality accidents don't weigh any more heavily than other kinds of accidents in the department's decision whether to install a traffic signal at a particular interchange, Rizek.

Specifically, the department decides in favor of a signal if the interchange in question has more than the statewide average of 10 accidents per 10 million entering vehicles in an urban intersection.

The K-32 and southbound K-7 ramp interchange met that criterion, Rizek said, while the northbound K-7 ramp interchange did not.

Rizek said she didn't have the traffic volumes for the two interchanges, but the total number of accidents at the southbound K-7 ramp interchange from 2000 to 2006 - the latest period for which accident data was available from KDOT - was 51, of which 29 were injury accidents. The northbound K-7 ramp interchange saw in those same years a total of 10 accidents, of which three were injury accidents.

There were no fatality accidents at either interchange in those years.

In addition to accident history and traffic volume, Rizek said, KDOT uses standards set in the Manual of Uniform Traffic Control Devices from the U.S. Department of Transportation's Federal Highway Administration. in its decision-making process for determining which interchanges get traffic signals.

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