Motorists who zip through red lights at certain Kansas City intersections soon will be paying for breaking the law.

It’s about time. Red-light runners endanger themselves, other drivers and pedestrians.

Early this year a contractor hired by Kansas City plans to install cameras at six intersections.

By Jan. 22 city officials hope cameras will be in place at 39th Street and Southwest Trafficway. After 30 days in which the city will raise public awareness of the cameras, they will start snapping pictures of red-light runners. That eventually will result in $100 tickets.

More than two years ago a citizens task force strongly supported camera use. The members emphasized improving public safety over collecting more money from tickets.

This is a key point because critics say other cities have shortened yellow-light times to catch more motorists running red lights, which increases revenues from traffic fines.

As a check against that, earlier this week The Star timed how long yellow lights lasted for northbound and southbound motorists at the six intersections where cameras will be placed.

The figures, from an average of seven readings at each intersection, timed between 2 p.m. to 4 p.m. and rounded to the nearest 10th of a second:

3.3 seconds at 19th and Walnut streets

3.8 seconds at 27th Street and Southwest Trafficway

3.9 seconds at 39th Street and Southwest Trafficway

3.8 seconds at 39th and Main streets

3.8 seconds at 63rd Street and Prospect Avenue

3.9 seconds at 79th Street and Wornall Road

The Star will follow up after the red-light cameras are installed to determine whether the city or the contractor has altered the yellow-light timing at these intersections.

A city official said this week that the city follows federal standards for programming yellow lights.

The federal Manual on Uniform Traffic Control Devices states: “A yellow change interval should have a duration of approximately 3 to 6 seconds. The longer intervals should be reserved for use on approaches with higher speeds.”

Dennis Gagnon, a Public Works Department spokesman, said the city does not plan to change the length of yellow lights and added: “We don’t want the red-light camera company meddling” with the timing of the lights.

The timing should not be altered at these or other intersections simply to pull in more revenue.