How Our Traffic Lights Work
Have you ever stopped to wonder how our traffic lights work?
Wichita Traffic lights actually run a few different ways, based primarily on how old they are. Check out the different methods used in Wichita.
Fixed-time Lights
The oldest type of traffic lights in Wichita are those that run on fixed-time. That means that the lights run on a timer, and that the amount time allotted for green and red lights does not change, regardless of the flow of traffic. These lights are used in Wichita’s downtown core.
"The benefit of a fixed-time light is that you’ll always get a green light, but you may have to wait for the light going the other direction to time out, even if there is no traffic" Brian Coon, Traffic Engineer for the City of Wichita said.
Most of Wichita’s lights have been upgraded from this system, however, to intersections that are semi-actuated or actuated.
Actuated and Semi-actuated Lights
At a semi-actuated light, traffic on one of the intersecting streets is detected by cameras. The street that is not monitored will always have a green light, unless traffic is detected from the other direction. An example of this occurs on Lewis and Main, where Lewis St. traffic is detected by cameras and Main stays green unless a car comes.
A fully-actuated intersection is equipped with cameras that detect traffic in all directions.
There is actually a common misconception about these kind of lights. Contrary to popular belief, the cameras atop traffic lights serve only to detect traffic, not to record video and aide in issuing traffic citations.
When lights are broken and need replaced, actuated and semi-actuated lights are used. The benefit of the semi-actuated and actuated traffic lights is that they allow for volume density, or for extended green lights depending on the flow of traffic, so when a car approaches an intersection, an additional green allowance will be made. The drawback to this approach, however, is that the cameras cost $4,000 each, so it costs the City $16,000 per intersection to upgrade to actuated lights. In addition to the expense, these types of lights are very maintenance-heavy, as adjustments have had to be made when cameras have mistaken tree shadows for cars and inhibited the flow of traffic for an exorbitant amount of time. The cameras can also become fogged over as a result of weather. During the winter, the brine used for the treatment of icy streets fogged up several Wichita cameras, slowing the traffic in multiple locations. When these things happen, each individually affected camera must be cleaned. Under these circumstances, a fixed time system is arguably a better system, but as previously noted, each have their benefits.
Inductance Loops
Another system that the city uses to detect traffic, though less frequently, is that of inductance loops. This system places coils of wire under the street's surface that electromagnetically detect the metal of the car, which serves as and inductor. These are rarely used because installation requires cutting into the the ground and are very hard on the roads. An additional drawback to this system is that it is harder to detect the presence of motorcycles and smaller cars as they have less inductive material.
Future Development
The city wants to know what streets Wichita citizens want to have optimized, as well as the best way to go about doing so. One major consideration is that when individual roads are optimized, it can delay side-road traffic. The city hopes to hire a consultant in the near future to help combat this issue. Well-aware of the frustrations delayed traffic can bring, the city must consider the safety of its drivers.
“There’s a balance between safety and efficiency. Our primary focus is safety, and we want to be as safe as possible,” said Coon.
Wichita's Busiest Intersections
Here are the top 10 busiest intersections in Wichita in 2015, according to a document on the city's website. These findings are based on how many vehicles passed through the intersection, from any direction, in 2015. (This number is half of the sum of the number of vehicles moving in each direction, as a vehicle that enters the intersection from the south and exits from the north is still one vehicle, even though it has crossed two sides of the intersection.) You can view the document in full here.
Kellogg and Webb with 69,046
Central and Ridge with 49,945
Central and Rock with 49,592
I‐235 Ramp and Zoo with 48,714
13th and Rock with 46,213.
Kellogg and Greenwich with 45,753
21st and Ridge with 45,521
Harry and Rock with 45,094
Kellogg Dr and Rock with 44,922
Westdale and Zoo coming in at 44,752.
Report an Issue
Call-in reports are a tremendous help to the city's traffic engineers.
"The public really helps us a lot by calling when traffic lights are behaving oddly, or camera lenses need to be cleaned. "
If you encounter a traffic issue that is potentially dangerous such as a downed stop sign, report it to 911 immediately. For non-dangerous issues such as downed street signs, call in reports to traffic maintenance at 268-4013, or email at traffic@wichita.gov.
If you find yourself stuck at a red light that does not recognize you presence, please act legally and responsibly and turn right on red when the road is clear, and report situation.
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