Traffic Control and You: GENERAL TRAFFIC FAQ's
Answering Common Questions
Q. Have You Ever Wondered...
How does my community decide where to place stop signs?
How are speed limits established?
Why aren’t there speed bumps and Children at Play signs in my neighborhood?
This document answers these and other commonly asked questions about traffic control. But first, it is important to know some of the terminology and history of traffic control and engineering.
Q. Who regulates traffic in Douglas County?
The Department of Public Works places and maintains traffic control devices, regulates traffic and studies and analyzes traffic flow to ensure safety and efficiency. Public Works follows a set of guidelines called The Manual of Uniformed Traffic Control Devices (MUTCD) to determine the appropriate use of traffic devices. This manual gives certain criteria that should be met before Public Works can use a particular device. These guidelines ensure that motorists have consistency among different communities throughout the country.
Q. What is traffic engineering?
Traffic engineers plan, design and monitor the roads, streets and highways to ensure safe, efficient and convenient movement of people and goods. These tasks include long-range transportation planning as well as recommendations for integrating freeways, streets, shopping centers, residential developments and industrial projects into the community that will serve the populations safely and efficiently.
Q. What are traffic control devices?
Traffic control devices include all the signs, signals, pavement markings and devices used to control traffic. These devices may be placed on, over or next to a roadway by a public official with the authority to regulate, warn or guide traffic.
Q. How do traffic signals work?
Pre-timed and traffic-actuated signals are the two types used on today’s roads. Pre-timed controllers operate on a regularly repeated sequence of signals and are used where traffic volume is stable and predictable. Traffic-actuated controllers change in response to traffic demand and are generally used where traffic volume fluctuates widely, and where interruptions to major street flow must be minimized.
Q. Won’t a traffic signal reduce accidents at our intersection?
Traffic signals can benefit the community and increase safety when used properly. However, traffic signals don’t always prevent accidents or help control traffic. In fact, while traffic signals generally reduce the number of right angle collisions, the number of rear-end and pedestrian accidents may actually increase.
For example, many pedestrians feel secure with a painted crosswalk and a red light between them and an approaching vehicle. The motorist, however, may not be as quick to recognize these barriers, thereby creating a false sense of security for the pedestrian.
To decide whether a traffic signal should be installed, the traffic engineers consider the following:
- Does the amount of traffic on intersecting streets create confusion or congestion?
- Is traffic on the main street so heavy that drivers on the side street will try to cross with it is unsafe?
- Do pedestrians trying to cross the busy street create confusion, congestion or hazardous conditions?
- Does the number of school children crossing a street require special controls for their protection? If so, is a traffic signal the best solution?
- Will a traffic signal at this location help drivers maintain a uniform pace along the route without unnecessary stops?
- Does the intersection’s accident history indicate that a traffic signal will reduce the possibility of a collision?
- Do two arterial roads intersect at this location, and will a signal improve the flow of traffic?
- Is there a combination of the above conditions that indicates a signal will be an improvement rather than a detriment?
Traffic engineers compare each situation with national standards established by studying intersections throughout the country. Intersections which fit the above criteria generally operate effectively to control traffic flow, while those that don’t meet the criteria may become additional hazards.
Q. What about a 4-way stop sign?
Like the traffic signals described above, 4-way stops should also meet criteria listed in the MUTCD, which included the following:
- Multi-way signs may be placed at an intersection temporarily while arrangements are being made for a traffic signal.
- The intersection has a high accident rate of five or more within a 12-month period.
- Traffic on the intersecting streets are at volume levels that make normal right-of-way rules ineffective.
Q. Why can’t we have a stop sign in our neighborhood to reduce accidents?
Installing an unnecessary stop sign as a "nuisance" or "speed breaker" may actually increase the number of accidents in the area. The unwarranted signs breed disrespect by motorists who tend to ignore the signs or slow down without stopping. Impatient drivers view the additional delay as "lost time’ to be made up by driving faster between signs.
Q. What are traffic control zones and how should I react?
Whenever construction is in progress on or near the roadway, drivers face rapidly changing traffic conditions. These changes can be hazardous for drivers, workers and pedestrians unless protective measures are taken.
An orange, diamond-shaped warning sign typically tells motorists of an approaching traffic control zone. These signs inform motorists of construction, maintenance and utility operations, but can include work activities such as survey crews and temporary weighing stations.
Traffic control zones are divided into several areas to increase safety for both workers and motorists. The areas include:
- Advance Warning Area - tells motorist what to expect.
- Transition Area - moves traffic out of its normal area.
- Buffer Area - provides protection for traffic and workers.
- Work Area
- Termination Area - lets traffic resume normal driving.
When traveling through these control areas, always be alert for workers and decrease your speed to increase safety.
Q. Why not lower the speed limit to reduce hazards in our area?
There is a common misconception that posting a speed limit will influence drivers to drive that speed. The facts indicate otherwise. Studies show that a driver’s speed is influenced more by the appearance of the road and the prevailing conditions than it is by posted speed limits and, in fact, unrealistically low speeds can actually cause accidents. Think, for example, about the times you have been stuck behind someone who was traveling much slower than the surrounding traffic and feel the urge to speed by them.
Q. Why can’t we use speed bumps on our block?
When posted speed limits fail to slow cars down in residential neighborhoods, people often request that speed bumps be installed in streets. However, speed bumps can cause more problems than they solve. They are a hazard to the unwary, a challenge to the daredevil, a disruption for emergency and maintenance vehicles and the cause of an undesirable increase in noise.
In addition, tests show that speed bumps are ineffective in controlling all types of vehicles. The driver of a softsprung sedan is encouraged to increase speed for a better ride over a speed bump, while other drivers may lose control at the same speed. For these and other reasons, Douglas County rejects the use of speed bumps as standard traffic control devices on public streets.
The control of speeding in residential neighborhoods is a widespread concern which requires persistent law enforcement efforts...not speed bumps.
Q. Won’t a "Children at Play" sign help protect our children?
Studies show no evidence that these signs prevent injury or decrease the speed of vehicles. They can give parents a false sense of security and since nearly every residential block has children living on it, there would have to be signs on each one. Blocks with no signs might imply that no children live there, so the driver does not have to watch out. Children could misinterpret the sign to mean that it is okay to play in the street.
To address pedestrian safety, specific warning signs for school zones, pedestrian crossings, playgrounds and other recreational areas are used where clearly justified.
Q. What can individuals do to help reduce traffic accidents?
Individuals can do their part by taking the following precautions:
- Obey the posted speed limit.
- Obey traffic control devices such as signs, signals and pavement markings. These devices were installed for your safety.
- Drive carefully and defensively. Use your seat belt and concentrate on your driving. Don’t drink and drive.
- Play it safe. Don’t try to "beat the train" or "beat the light"
- Use your headlights between dusk and dawn and any time visibility is reduced by rain, smoke, fog, etc.
- Report roadway hazards as soon as possible. For example, report the following:
- traffic signs obstructed by vegetation
- traffic signal malfunctions
- traffic signs down or damaged
- obstructions potholes, bumps or dips in road
- Keep your vehicles in good mechanical condition by regularly checking brakes, tires, wipers and other safety equipment.
- Keep vegetation on your property trimmed to ensure good intersection, traffic control sign and driveway visibility.
Q. What can pedestrians do to reduce pedestrian accidents?
- Play it safe and use common sense. Don’t take unnecessary chances, like running in front of an oncoming car.
- Expect the unexpected. Pay attention to your surroundings and do not let cars surprise you, even is a motorist runs a stop sign or makes a sudden turn.
- Walk facing oncoming traffic. When there is not a sidewalk, walk near the curb or off of the road, if possible.
- Cross streets at intersections whenever possible. Don’t jaywalk.
- Look both ways before crossing the street and watch for cars turning right on red.
- Use crosswalks but don’t think you are safe just because you are inside it.
- Use the push-button Walk/Don’t Walk signal. Begin crossing when the Walk signal appears. If the Don’t Walk signal begins flashing while you are in the street, continue quickly and carefully to the other side. However, don’t start across the street when the Don’t Walk is blinking. A steady Don’t Walk means wait for the Walk signal. An easy way to remember is Walk means go, and Flashing Don’t Walk means caution and a Steady Don’t Walk means stop. (Sort of like a traffic light)
- Be careful in parking lots. They can be even more dangerous than the street because cars are moving in all directions, including backwards. Drivers often forget that pedestrians have the right-of-way.
For further assistance and to report problems:
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For emergencies, please contact the Douglas County Sheriff’s Department at 303.660.7500.