Regulatory Signs: Speed Limits, Stop, Yield, Prohibition, and Mandatory Direction
Regulatory signs: the law in sign form
Regulatory signs tell you what you must or must not do. In Oklahoma they follow the MUTCD: most are white rectangles with black legends; STOP is the red octagon, YIELD the red-and-white triangle. A STOP sign requires a complete stop at the stop line, crosswalk, or edge of the roadway before proceeding. At a 4-WAY plaque, the first vehicle to stop goes first; if two stop together, the driver on the right goes first. YIELD means slow or stop as needed to let cross traffic and pedestrians clear.
Speed limit signs are white with black numerals. They set the maximum lawful speed in ideal conditions; slower is required in rain, ice, or poor visibility. Minimum speed signs (white with black numerals and "MINIMUM") apply only where posted. Prohibition signs use a red circle with a slash over the forbidden action-no left turn, no U-turn, no trucks. Mandatory direction signs use arrows to show the only lawful movement; a white arrow on black is common for lane-use control.
Worked example: You reach a four-way stop at the same time as a truck on your right. You want to turn left. Who goes? The truck has the right-of-way because it is on your right; you wait. If the truck waves you through, proceed only after confirming no other vehicle is moving.
Traps: treating YIELD as a suggestion; rolling through a stop when turning right; reading a "No Right Turn" sign as applying only during school hours; and obeying an advisory speed plaque as if it were a speed limit. Also watch for "EXCEPT" plaques-they narrow a prohibition.