Road Signs in Atlanta

US (United States) newly installed BPS (purple) toll road signs. It is unusual for signs meant for roads to be made of purple color that are put up for the first time.

HC (hazardous cargo) traffic signs either permissive or prohibiting entry of any vehicle transporting harmful substances. Therefore, they are very few of these highly specific markings regulating hazardous materials transportation.

Signs warning of an "Invisible Cow". Such markers indicating difficult-to-discern cow presence at the motorway exist peripheryly.

“Warthogs and Children Have Right of Way” signals. It is very unusual to find traffic signs favoring a warthog in place of a man.

“Wheelchair Alligator” signs have an exceptionally bizarre design and are very infrequent on roads’ sides worldwide—a category that includes alligators sitting down in wheelchairs.

Generally speaking, rare road symbols are rare because they tend to be highly specialized or unique in an often humorous rather than just regulatory way.

The 7 main types of traffic signs are:

Regulatory signs (white or red background): These signs convey traffic laws and regulations that drivers must obey, such as stop signs, speed limits, and turn restrictions.
Warning signs (yellow or fluorescent yellow-green background): These signs alert drivers to upcoming road conditions or hazards, such as curves, intersections, or school zones.
Guide signs (green, blue, or brown background): These signs provide directional information to help drivers navigate, such as route markers, destination signs, and service signs.
Stop signs (octagon shape): These red signs with white lettering instruct drivers to come to a complete stop.
Yield signs (inverted triangle shape): These red signs with white lettering tell drivers to slow down and yield the right-of-way to other vehicles or pedestrians.
Diamond-shaped signs: These yellow signs warn drivers of upcoming road conditions or hazards.
Pentagonal signs: These signs indicate school zones where extra caution is required.
The shape, color, and symbols on traffic signs all convey specific information to drivers to promote safety and efficient traffic flow/

The most common red signs are:

Red road signs in the United States are used for regulatory signs that convey traffic regulations that require drivers to take immediate action to avoid threats to traffic safety.

Stop signs - Drivers must come to a complete stop before proceeding
Yield signs - Drivers must slow down and yield the right-of-way to pedestrians and oncoming traffic before proceeding
Do Not Enter signs - Prohibits access or entry
Wrong Way signs - Indicates the driver is going the wrong way on a one-way street

Red is also used for the octagonal stop sign and inverted triangle yield sign shapes. Other regulatory signs like turn prohibition signs (No Right Turn, No Left Turn) have a red circle and slash symbol.

In summary, red is reserved for the most critical regulatory signs that require drivers to stop or yield to avoid collisions. The red color immediately alerts drivers to a mandatory traffic law or safety hazard ahead.