Traffic Control Devices

Traffic control devices are essential tools used to manage the flow of vehicles on public roads. They help to keep traffic moving smoothly, and prevent accidents that could lead to loss of life or property. Traffic control devices in Austin Texas come in many shapes and sizes, with a wide variety of functions. Some of the most common are barriers and lane closures. These can be placed to mark the start or end of a work zone, or to act as a barrier that stops cars from accessing a highway or vice versa. Barriers can also be placed to block off water spots on the road that may cause damage or impede the flow of traffic.

The most important function of any traffic control device is to protect people. Without them, the roads would be a dangerous place to be. They provide a safe environment for both motorists and workers on the road. The Traffic Control Devices are available in different colors, shapes and sizes, depending on their purpose. Some are very visible to drivers with bright lights and reflective materials. Others are more discreet, and only noticeable when a driver approaches them.

A Traffic Signal is a device that assigns right of way to approaching vehicles at intersection or midblock locations. It can be a red or green octagon with the letters, S-T-O-P, or it can be a yellow triangle with the words STOP. These are the most commonly seen Traffic Control Devices. The Texas Manual of Uniform Traffic Control Devices specifies how these should be displayed, including when a two-way stop is required.

Signal timing is controlled by a traffic controller unit, which selects and times the signal lamp display sequences. The traffic controller is a complex electrical apparatus with several circuits that perform a variety of functions.

Early controller units were electromechanical, with a solenoid-driven camshaft for lamp switching and vacuum tube circuitry for timing functions. The traffic engineer adjusted interval and phase timing with knobs on the control panel. These analog units generated considerable heat, requiring forced-air circulation and filtering in the controller cabinet to avoid overheating.

Newer traffic signal systems have replaced these older units with more efficient, computer-based control logic. They still use the same physical components, but have replaced the vacuum tubes with digital microprocessors that communicate with a central traffic control unit via either a serial or Ethernet port. The traffic control center then adjusts the signal timing to synchronize it with other signals in the system.

In most cases, traffic signal controllers can be operated in isolation or coordinated mode. In isolated mode, the signal operates independently from other traffic signals. Coordinated control requires synchronizing the signal’s operating cycle with those of adjacent signals to ensure that all approach phases are served at the same time.

A traffic signal coordinator uses a third-party time source such as a radio receiver, cell phone time monitor or Internet connection to periodically update the signal’s clock and to select the appropriate operating cycle for each phase. Even traffic signals under the command of different central computers can be coordinated as long as all controllers have their clocks set to a standard reference.