The shapes and colors of traffic signs are important. You should know signs by their appearances so when driving you can recognize them at a distance even when visibility is poor.
There are ten colors and nine shapes of traffic signs. Each shape and each color has an exact meaning, so you must acquaint yourself with all of them.
Expect one or two questions about shapes and colors on your knowledge test. Pay special attention to signs that have exclusive use.
Octagon: Exclusively used for Stop.
Equilateral Triangle (One point down): Exclusively used for Yield.
Circle: Grade Crossing Advance Warning.
Pennant Shape (Isosceles Triangle): Exclusively used for No Passing.
Pentagon (pointed up): Exclusively used for School Advance Warning Sign.
Crossbuck (two rectangles in an X configuration): Exclusively used for Grade Crossing.
Diamond: Warning signs.
Rectangle (including square): Used for Regulatory signs (often vertical), Guide signs (often horizontal), and Warning signs.
Trapezoid: Used for Recreational and Cultural Interest Area signs, and National Forest Route signs.
In addition, Interstate Route signs consist of a cutout shield, with the route number in white letters on a blue background. Many route sign designs are established locally.