FAQ's

Traffic Division

Public Works

Traffic - FAQ's

On this page:

• Stop Signs at intersections?
• “Children at Play” signs?
• Speed humps for our neighborhood?
• Why does my streetlight cycle on and off?
• How do traffic signals work?
• “DONT WALK” before I cross the street?
• When is a crosswalk unsafe?
• Why don’t we just reduce the speed limit?
• Do I need to call someone when digging in my yard?
• Traffic signal indications red, yellow, and green?

Why are there not Stop Signs at more intersections?

Stop signs are one of the most effective sign control devices when used at the right location and under the right conditions. The Manual on Uniform Traffic Control Devices defines the appropriate use of stop signs and stresses that they are not to be used for speed control. A stop sign is intended to help assign right-of-way for drivers and pedestrians at an intersection.

Stop signs that arbitrarily interrupt traffic or cause such an inconvenience as to force traffic to use other routes are “nuisances” and typically cause a high incidence of intentional violation. When vehicles do stop at warranted stop signs, the speed reduction is effective only in the immediate vicinity of the stop sign, and frequently speeds are higher between intersections.

Well-developed, nationally recognized guidelines are followed for the placement of stop signs in our City.

Why doesn’t the City put up “Children at Play” signs?

Widespread public faith in traffic signs to provide protection and parental concern for children’s safety results in frequent requests for this type of signage. Although some area cities have posted these signs in residential areas most have or are beginning to remove them.

There is no evidence to document the success of these signs in reducing pedestrian accidents or operating speeds. In fact these signs can give parents and children a false sense of security and potentially increase risk of accidents. Because of these considerations the City of Shawnee does not use “Children at Play” signs.

How can we get speed humps for our neighborhood?

Although speed humps are gaining national attention as a means of traffic calming there are numerous cases across the country where speed humps have been installed and later removed, as the desired effect was not obtained.  As of 2003, there are only five speed humps on public streets in Johnson County.  Great consideration and planning should go into their design and placement.

A speed hump for a public street is significantly different than what you see in a private parking lot.  The small four inch wide and two inch high bump that grabs your attention in the parking lot is not allowed on a public street for safety reasons.  A speed hump for a public street will be three to four inches high and twelve or twenty two feet long.

At this time, our City does not promote the installation of speed humps for traffic calming. While speed humps may slow down most drivers, a percentage of drivers will still travel at a high rate of speed in between the humps or occasionally do not slow down at all for the hump itself.

Why does my streetlight cycle on and off?

Most of the streetlights in our City consist of high pressure sodium lamps. These lamps are designed to average a life of 24,000 hours, or appropriately six to seven years on the street. These lamps begin to incur problems when they near the end of their lives and begin to “cycle” on and off. The bulb overheats, goes out, cools down, then lights again.

If you notice a cycling light, contact the Public Works Traffic Division with an address or description of the streetlight location.

How do traffic signals work?

Have you ever wondered how a traffic signal knows your car is there? Ever wonder why sometimes you seem to wait forever for that green light? In reality, no permanent traffic signal in Shawnee has more than a two-minute cycle length when working properly. Each traffic signal location runs a unique timing program that includes maximum and minimum green times for each direction. Typically, when no car is present at an intersection, a traffic signal rests in green for the major street. When vehicles are present in multiple directions, the signal controller distributes green time based on its timing program.

The key to vehicle detection is the traffic loops placed in the travel lane for each direction. These loops are a coil of wire that induces a current that is detected by the signal controller when a metal object passes over them.

Each direction of travel is assigned a minimum and a maximum amount of green time. Minimum times are long enough for one or two cars to clear the intersection and for a pedestrian to cross the street. If there is no vehicle on the traffic loop and the minimum time has expired the next phase of the cycle will begin.

Maximum times are also assigned to assure that all lanes of traffic get a green signal. For example without a maximum time limit defined, Shawnee Mission Parkway would be green all day long as vehicles pass over its traffic loops. When the maximum time is reached, that phase will go to yellow even if cars are still coming. The next phase begins.

If you observe a maintenance problem or signal light out at any of our traffic signals, contact us immediately. If you think a timing improvement could be made please contact us during business hours and we’ll start a field review.

Why does it always say, “DONT WALK” before I cross the street?

The Walk or pedestrian symbol indication is displayed for a short period of time. The intent of this symbol is to let the pedestrian know that it is time to enter the crosswalk and begin crossing the street.

The Don’t Walk or raised hand symbol indication begins flashing at the end of the Walk interval and alerts pedestrians that it is too late if they have not already started to cross. The flashing Don’t Walk interval is timed so that it is long enough for a person walking an average speed to entirely cross the intersection.

When is a crosswalk unsafe?

A five year study was completed that included 400 intersections in San Diego, California, to investigate the relative safety of marked and unmarked crosswalks. The outcome was surprising. About two and one half as many pedestrians used the marked crosswalk; but, about six times as many accidents were reported in the marked crosswalks. Several other studies have since been completed with similar results.

One explanation for this contradiction of common sense is the false security pedestrians feel at a marked crosswalk. Painted lines do not provide protection against an oncoming vehicle and the pedestrian is just as responsible for his or her safety as the motorist. A pedestrian can stop in less than three feet while a vehicle traveling at 25 miles per hour will require 60 feet. Marked crosswalks at locations that do not have consistent pedestrian crossing patterns also tend to become invisible to motorists over time.

Why don’t we just reduce the speed limit?

Setting the speed limit below what the majority of motorists are driving does not reduce the speed of traffic. Most drivers choose a speed that feels right given the condition of the road. If we set the limit lower than what the driver feels it should be, it will be ignored by most.

Do I need to call someone when digging in my yard?

Yes! Any time you plan to excavate or dig on your property, even for a fence or tree, you should contact the free service of Kansas One Call at 1-800-DIG-SAFE.

This service contacts all of the utility companies, including the City of Shawnee, who have indicated they may have a buried utility on your property. The utility companies then have two working days after the receipt of your call to visit and mark their utilities at your described location. This service can prevent possible injury or a disruption in your neighborhood services.

The City of Shawnee receives over 16,000 cable locate requests each year from Kansas One Call.

How did traffic signal indications become red, yellow, and green?

In 1868 the first known gas powered traffic signal was installed in England for pedestrian and horse carriage traffic. In the 1880s red and green lanterns with candles controlled railroad traffic. The railroads decided that red should mean stop and green, go. As motor vehicles became popular, railroad signals were adapted for use on the roads. Garrett Morgan invented an electric traffic signal using the railroad colors of red and green. The first electric traffic light is believed to have been installed in Cleveland, Ohio, in 1914. After the early signals were in use it was determined that a clearance time was needed in order to tell the drivers to slow down. Engineers first decided to turn on both the red and green lights at the same time for a period of three seconds. Drivers thought the red and green looked orange/yellow so the new yellow caution signal was added in the late 1920's.