What are Traffic Control Devices and what are they used for?
Traffic control devices are signs, signals, pavement markings, and other devices placed along highways and streets to move vehicles and pedestrians safely and efficiently. These devices are placed in key locations to guide traffic movement, control vehicle speeds, and warn of potential hazardous conditions. They also provide important information to drivers about detours and traffic delays.
The main purpose of a traffic control device is to provide information to drivers so they can operate their vehicles safely along a highway or street. The five basic criteria of a traffic control device are to:
- Fulfill a need
- Command attention
- Convey a clear, simple meaning
- Command respect from road users
- Give adequate time for response
Signs, signals, pavement markings, cones, barricades, and warning lights are designed with specific colors, shapes, and sizes based on the different functions they provide. Uniformity of design (color, shape, size, and location) helps drivers to quickly understand the message of traffic control devices. Consistency is important for driver respect, recognition, and proper reaction to the devices.
Traffic control devices work in concert with the basic rules of the road contained in traffic laws and ordinances, including each State’s uniform code that regulates vehicle movements. One example is the right-of-way principle that determines which driver has priority when approaching or entering an intersection.
The primary resource for determining the design and use of traffic control devices is the Texas Manual on Uniform Traffic Control Devices (TMUTCD). The 2011 Edition revision 2 of the TMUTCD is the standard applicable to all public roads in Texas. The TMUTCD provides standards, guidance, and application information for signs, markings, traffic signals, and other traffic control devices.
Additional basic design guides have been produced by the Institute of Transportation Engineers such as the Traffic Engineering Handbook and Traffic Control Devices Handbook.
The goal of the Flower Mound Transportation Services Division is to ensure the proper use of traffic control devices by: installing the proper device for the situation; placing the device in the proper location; making sure that the proper color, size, and shape are used; removing obsolete devices; and properly maintaining traffic control devices. For more information on traffic control devices email David Stallings.
What is the purpose of a STOP sign?
The STOP sign is a regulatory sign that is used when traffic is required to stop. It is a red octagon that has a white border and the large white letters, S-T-O-P. At multi-way stop intersections, a small plate is placed below the stop sign to inform the driver of how many approaches are required to stop.
The Texas Manual of Uniform Traffic Control Devices (TMUTCD) describes STOP signs (R1-1), including applications and placement. STOP signs are used to assign right-of-way at an intersection. Since a STOP sign causes inconvenience to motorists, it should be only used where warranted.
Where should two-way STOP signs be installed?
Intersections must have one or more of the following conditions for two-way STOP signs to be installed:
- An intersection of minor and major road, where the application of the normal right-of-way rule would be hazardous
- A street that enters a highway
- An unsignalized intersection in a signalized area
- Locations where there is a combination of high-speed traffic, restricted view, and a previous crash record that indicates a need for STOP sign control.
The advantage of a two-way stop is that the major flows do not have to stop and they incur almost no delay at the intersection (i.e., the majority of the traffic does not have to stop).
Where are Four-Way (Multi-Way) STOP Signs Installed?
Four-way STOP signs are often used at the intersection of two roadways that exhibit approximately equal traffic volumes. The primary considerations for installation of a multi-way stop include the following:
- A traffic signal is going to be installed and the intersection needs a temporary solution to control the traffic
- Within 12 months, at least 5 crashes have occurred at the intersection that could have been prevented by STOP signs. Previous crash records include right- and left-turn collisions, as well as right-angle collisions
- Minimum traffic and pedestrian volumes - 200 vehicles per hour on minor street approaches and 300 vehicles per hour on major street approaches for 8 hours in a day
Other conditions that should be considered when determining the need for a multi-way stop include:
- The need to control left-turn conflicts
- The need to control vehicle/pedestrian conflicts near locations that generate high pedestrian volumes;
- Locations where a road user, after stopping, cannot see conflicting traffic and is not able to safely negotiate the intersection unless conflicting cross traffic is also required to stop
- An intersection of two residential neighborhood collector (through) streets of similar design and operating characteristics where multi-way stop control would improve traffic operational characteristics of the intersection.
To request a new STOP sign email Matthew Hotelling.
What is the purpose of a Traffic Signal?
Traffic signals are used to assign vehicular and pedestrian right-of-way. They are used to promote the orderly movement of vehicular and pedestrian traffic and to prevent excessive delay to waiting traffic.
Traffic signals should not be installed unless one of the warrants specified by the Texas Manual of Uniform Traffic Control Devices (TMUTCD) has been satisfied. The satisfaction of a warrant is not in itself justification for a signal. A traffic engineering study must be conducted to determine if the traffic signal should be installed.
The installation of a traffic signal requires sound engineering judgment and must balance the following, sometimes conflicting, goals:
- Moving traffic in an orderly fashion
- Minimizing delay to vehicles and pedestrians
- Reducing crash-producing conflicts
- Maximizing capacity for each intersection approach
To request a new Traffic Signal contact email Matthew Hotelling.
What are all the devices on many Town Traffic Signals?
We often receive questions about the various items that are found on many of the Town's traffic signals; most commonly what they are and what purpose they serve. Take a look at this photo collage, taken at the intersection of FM 1171 and Morriss Road. Here is a short description of the equipment:
- Wireless Communication: Used by the Town’s Transportation Staff to communicate remotely with the traffic signal equipment through the Advanced Transportation Management System.
- Traffic Camera: Monitors the flow of vehicles in and around the intersection, and serves as a resource for incident management by Emergency Services to monitor roadways in real-time. This device does not record any information.
- Wind Damper: Reduces the amount that a signal mast arm moves during high wind occasions. Typically placed on signal arms that are longer than 25-feet in length.
- Red Light Confirmation: Used by the Police Department to quickly identify which approaches have a red light from any direction. This device allows officers to safely and effectively monitor an intersection for red light violations.
- Vehicle Detection Camera: Detects the presence of a vehicle approaching/waiting at an intersection. These devices do not record any information, and are not “Red Light Enforcement” cameras.
- Emergency Vehicle Detection: Allows emergency vehicles to change the signal indication for their particular approach to green. This provides our first responders a faster and safer response to an emergency.