Sign Colors, Shapes, and Symbols
Color and shape are the fastest read on any sign: before you can read the words, the silhouette tells you what kind of message is coming. The exam leans on this because real driving does - a faded, snow-covered or night-time sign is often identifiable only by outline and color, and the shape plus color is enough to choose a safe response.
Colors
Red means stop, yield, prohibit or danger: STOP, YIELD, DO NOT ENTER, WRONG WAY, NO TURN ON RED. Yellow means warning. Fluorescent yellow-green means pedestrian, school or bicycle warning. Orange means work zone. Green means guidance and destinations. Blue means motorist services and information. Brown means recreation and cultural interest. White with black legend means regulation, such as a speed limit or parking rule. Purple may be used with electronic toll collection.
Shapes
Octagon: STOP, and only STOP. Inverted triangle: YIELD. Pennant: NO PASSING ZONE. Diamond: warning. Vertical rectangle: regulatory. Horizontal rectangle: guide. Circle: railroad advance warning. Crossbuck X: railroad crossing. Pentagon: school zone or school crossing. Trapezoid: recreational area. Shield: route marker. Each shape is reserved for one family of message, which is why an unreadable legend can still be decoded.
Symbols
A red circle with a diagonal slash means prohibited. Arrows show direction or lane assignment. A bicycle, pedestrian, deer or tractor symbol names the hazard the warning refers to.
Worked example
At dusk a driver sees a downward-pointing triangle with a red border but cannot read the legend. The shape alone identifies it as YIELD: slow down, check for cross traffic, and stop if the way is not clear. YIELD is the only inverted-triangle sign in the manual, so the silhouette is conclusive.
Traps
Treating a yellow diamond as a rule rather than a warning; confusing the round railroad advance sign with a regulatory circle; and failing to recognize a fluorescent yellow-green pentagon, which warns of children rather than setting a speed limit.