Engineers look at everything from speed to approach elevation and turning lanes. It's whats decided with that data thats handled differently.

It's not computers, but the programming that has people stopped.

"It's finding that balance to where it's the safest possible and it also serves its function," Supervising Traffic Engineer Scott Bitterman said.

Columbia Mayor Darwin Hindman proposed adding an all clear period to every city stoplight. An all clear period is a time at an intersection when all the lights are red. Engineers use this to prevent collisions between changing directions of traffic.

On the south side of Columbia, Intermediate Traffic Studies Specialist Brandon Campell double checks the first day for this intersection at Discovery Parkway.

"We like to check and see that everything is physically functioning, that there aren't any bulbs burnt out and that coordination is working well," Campbell said.

He knows it's difficult to get traffic and stoplights up to speed.

"At MoDOT we tend to view the yellow and the all red as a package deal. And we base our timing on that on an equation that takes into account several factors."

"We want a situation where the roadway sees a similar situation every time they go through a traffic signal. That way they're not surprised by anything, and they're not put in any danger."

The 31 page printout from MoDOT's Engineering Policy Guide includes the detailed equations for how MoDOT times signals.