Signs, Signals and Pavement Markings
Signs by color and shape
Color tells you the job of a sign before you read it. Red means stop or prohibit; white with black text is regulatory; yellow diamond warns; orange marks construction and maintenance; green guides; blue shows services; brown indicates recreation. Shape matters too: octagon is always stop, inverted triangle always yield, diamond warns, pentagon marks a school zone, and the round yellow sign with an X predicts a railroad crossing.
Signals
A solid red means stop and stay stopped. Right on red is allowed after a full stop unless a sign prohibits it; left on red is allowed only from a one-way street onto another one-way street. Flashing red behaves like a stop sign. Flashing yellow means proceed with caution. A steady yellow warns that the light is changing, so stop if you safely can. A green arrow gives a protected turn, but check for vehicles clearing the intersection.
Pavement markings
Yellow lines separate traffic moving in opposite directions; white lines separate lanes moving the same way and mark the right edge. A broken yellow line on your side permits passing when safe; a solid yellow line on your side prohibits it; double solid yellow prohibits passing in both directions. Broken white lines permit lane changes; solid white lines discourage them. A shared center left-turn lane is for turning only, never for travel or passing.
Worked example
You see a broken yellow line on your side and a solid yellow line on the other. Reasoning: the marking is read from the driver's own side, so you may pass when the road ahead is clear, while oncoming traffic may not. Passing still requires adequate sight distance and no posted no-passing zone.
Traps that cost marks
Speeding up on yellow; treating flashing yellow as a stop; misreading which side of a two-way centerline applies to you; using the shared center turn lane as a travel lane; assuming worn markings are optional in rain.