Laws Regarding Green Traffic Lights

Standardized traffic signals are designed to command the attention of road users.

It is a federal requirement that traffic signals on roads open to public use must conform to the Federal Highway Administration's "Manual on Uniform Traffic Control Devices" (MUTCD). The MUTCD defines the warrants for justifying the installation of a traffic signal and defines traffic signal design and operations requirements.

Meaning

A standard meaning for each color (red, yellow and green) and shape (round ball, arrow, etc.) on a traffic signal face is defined in the MUTCD. A circular green traffic indication means vehicle traffic can proceed straight through a midblock location or intersection, or turn (right, left, u-turn), unless the movement is otherwise prohibited. Pedestrians facing a circular green indication are also permitted to cross a roadway.

Steady and Flashing Modes

Signal indications use steady and flashing displays. While circular red and yellow indications can be put into flashing operation for specific applications, the circular green indication is always used in a steady (non-flashing) mode.

Position on a Traffic Signal Head

Traffic signal heads can be mounted either vertically or horizontally. In a typical vertical display, place the circular green indication below the yellow indication, and above any arrow indications. In a typical horizontal display, the place the red indication on the far left and the green indication to the right of the yellow indication.

References

• Federal Highway Administration: Manual on Uniform Traffic Control Devices, 2009