Warning signs

Key points

1. Most warning signs are black on yellow and diamond shaped; they warn of an unexpected condition.

   Source: Handbook p. 49

   “Most warning signs are black on yellow and diamond-shaped. They also include the fluorescent yellow/green school warning signs. These signs warn you about an unexpected condition.”
   Idaho Driver's Handbook, Handbook p. 49

2. An Open Range sign means livestock have the right of way and may roam freely and unfenced.

   Source: Handbook p. 49

   “You are traveling in an area where livestock have the right-of-way and are allowed to roam freely and unfenced.”
   Idaho Driver's Handbook, Handbook p. 49

3. At a 3 way T intersection, stop and yield to drivers from the other two directions.

   Source: Handbook p. 49

   “You are approaching a 3-way “T” intersection and will have to turn either to the right or the left. You must stop and yield to drivers approaching from the other two directions.”
   Idaho Driver's Handbook, Handbook p. 49

4. A Lane Ends sign means two lanes will soon become one, and merging traffic must yield.

   Source: Handbook p. 50

   “Two lanes of traffic will soon become one lane of traffic. Merging traffic must yield.”
   Idaho Driver's Handbook, Handbook p. 50

5. At a School Crossing sign, watch for children, reduce speed and obey crossing guards; the sign may be yellow or fluorescent yellow green.

   Source: Handbook p. 51

   “Watch out for children, reduce speed, and obey crossing guard signals. The color of this sign may be yellow or fluorescent yellow/green.”
   Idaho Driver's Handbook, Handbook p. 51

6. At a Pedestrian Crossing sign, pedestrians have the right of way and you may have to stop.

   Source: Handbook p. 51

   “Pedestrians have the right-of-way, and you may have to stop for them.”
   Idaho Driver's Handbook, Handbook p. 51

7. A Hill sign warns of a steep downhill; check your brakes first.

   Source: Handbook p. 52

   “This sign is a warning to all vehicles that the road goes down a steep hill. You should check your brakes before going down the hill.”
   Idaho Driver's Handbook, Handbook p. 52

8. The pennant shaped No Passing Zone sign is on the left side of the road.

   Source: Handbook p. 52

   “This pennant-shaped sign will be on the left-hand side of the road or highway”
   Idaho Driver's Handbook, Handbook p. 52

Numbers to know

Recognize these signs

3 questions from the Idaho practice test

1. 1. What shape and color identify most warning signs in Idaho?

   1. Black lettering on white rectangles
   2. White lettering on green rectangles
   3. Black symbols or lettering on yellow, usually diamond-shaped
   4. Blue symbols on circular signs
   Show answer

   Black symbols or lettering on yellow, usually diamond-shaped. Most Idaho warning signs use black on yellow and a diamond shape. This visual combination alerts drivers that an unexpected condition may be ahead, so they should look for the hazard and prepare to slow or take another safe action. Green rectangles normally provide guide information, white regulatory signs communicate rules, and blue signs commonly identify services. The diamond is the quick recognition cue. Read the symbol or wording next, then adjust speed before reaching the condition described.

2. 2. What does the yellow diamond Intersection/Crossroad warning tell you to watch for?

   
   1. A divided highway ending at a toll station
   2. A guaranteed green signal at the next block
   3. A railroad gate that must remain closed
   4. A road crossing ahead and possible cross traffic in your path
   Show answer

   A road crossing ahead and possible cross traffic in your path. The Intersection/Crossroad warning means another road crosses the one you are using, so traffic may enter across your route. Scan both sides, control your speed, and be prepared to yield or stop if the intersection requires it. The green-signal choice invents a signal phase that the sign does not promise. A railroad gate and a toll station describe unrelated facilities. Treat the diamond as advance notice, then let the actual traffic control device and other road users determine when you proceed.

3. 3. Which colors may a School Crossing warning sign use?

   1. Red or purple
   2. Blue or white
   3. Orange or black
   4. Yellow or fluorescent yellow-green
   Show answer

   Yellow or fluorescent yellow-green. The handbook says the School Crossing sign may be yellow or fluorescent yellow-green. Those colors make the warning visible while the sign alerts drivers to children and a crossing area. Blue and white identify other sign purposes, orange and black commonly mark work zones, and red or purple is not the listed combination here. Do not treat the color detail as permission to maintain speed. The same sign still calls for attention, reduced speed, and obedience to crossing guard signals when they are present.

Source: the Idaho Driver's Handbook, Highway & Vehicle Knowledge. This lesson is a plain English summary, not the law itself; where it differs, the manual and the statute govern. Last checked 2026-09-27.