permit test (sign shapes & colors)

circular signs

alert drivers of upcoming railroad crossings

orange signs

construction and maintenance warning, traffic warnings

yellow signs

general warning, road conditions or hazards, school zones/pedestrian signs, etc

green signs

guide signs, information, permitted movements/directions, highway entrances/exits

pennant-shaped signs

left-hand side of two-way zones to warn drivers not to pass other drivers on the left

brown signs

parks and recreation signs

red signs

prohibitive or stop, immediate action to avoid threats to traffic safety

rectangular signs

regulations drivers must obey, helpful info like route markers, hazardous conditions

white signs

regulations, speed limits, highway markers, no turn on red

blue signs

services, evacuation routes

equilateral signs

slow down, prepare to come to stop

five-sided signs

warn drivers they're entering an area near school, children school crossing sign

eight-sided signs

warn drivers to stop and yield

diamond-shaped signs

warn of upcoming road conditions and hazards