Warning Signs

Key points

1. Warning signs are diamond shaped with a yellow background and black letters.

   Source: Handbook p. 21

   “WARNING SIGNS are diamond-shaped, with a yellow background and black letters.”
   Oklahoma Driver Manual, Handbook p. 21

2. They signal hazards, changes in direction or other conditions immediately ahead; be prepared to use extra caution or to make changes as you drive.

   Source: Handbook p. 21

   “They signal conditions immediately ahead, such as road hazards, changes in direction or other situations. When you see a warning sign, be prepared to use extra caution or to make changes as you drive.”
   Oklahoma Driver Manual, Handbook p. 21

3. A merge sign means other traffic may move into your lane; adjust your speed and lane.

   Source: Handbook p. 21

   “Merge. Other traffic may be moving into your lane. Be ready to change your speed and lane so other drivers can merge safely.”
   Oklahoma Driver Manual, Handbook p. 21

4. An added lane sign means two roadways join with a new lane, so you do not have to merge.

   Source: Handbook p. 21

   “Two roadways come together ahead with a new lane added. You do not have to merge”
   Oklahoma Driver Manual, Handbook p. 21

5. A two way traffic sign means drive in the right lane and expect oncoming traffic on the left.

   Source: Handbook p. 21

   “Two-way traffic ahead. Drive in the right-hand lane and expect oncoming traffic in the left-hand lane.”
   Oklahoma Driver Manual, Handbook p. 21

6. At a pedestrian crossing sign, slow down, prepare to stop and yield.

   Source: Handbook p. 21

   “Pedestrian Crossing. Slow down and prepare to stop. Watch both sides of the street. You must yield.”
   Oklahoma Driver Manual, Handbook p. 21

7. At a steep hill sign, approach with caution; a lower gear can help slow the vehicle.

   Source: Handbook p. 21

   “Steep hill ahead. All drivers approach with caution. You may want to use a lower gear to slow your vehicle.”
   Oklahoma Driver Manual, Handbook p. 21

8. Diagonal stripes on a warning sign or barricade show which side traffic should pass.

   Source: Handbook p. 22

   “The diagonal stripes on a warning sign or barricade show the direction in which the traffic is to pass.”
   Oklahoma Driver Manual, Handbook p. 22

Recognize these signs

3 questions from the Oklahoma practice test

1. 1. What do yellow diamond warning signs generally signal?

   
   1. The route number of the highway being traveled
   2. Services available at the next roadside stop
   3. A legal requirement to carry proof of insurance
   4. Conditions immediately ahead, such as hazards or changes in direction
   Show answer

   Conditions immediately ahead, such as hazards or changes in direction. Yellow diamond signs warn about conditions close enough ahead to affect the next driving decision. Those conditions can include a road hazard or a change in direction, so the driver should scan ahead, adjust speed, and be prepared to stop or steer as needed. A roadside service sign gives facility information, insurance proof is a legal responsibility, and a route number identifies travel direction rather than a hazard. The useful cue is the yellow diamond shape: treat it as an advance warning, then look for the specific roadway feature shown by its symbol.

2. 2. A yellow warning sign shows a clearance height before an underpass. What does it warn about?

   1. The lowest speed allowed in the underpass
   2. The width of the narrow bridge ahead
   3. Vehicles or loads higher than the height shown cannot go through
   4. The distance to the next exit
   Show answer

   Vehicles or loads higher than the height shown cannot go through. A low clearance sign gives the height of the opening ahead. If your vehicle or its load is taller than that number, it cannot pass through the underpass, and you need a different route before you reach it. Drivers of tall vans, trucks, and vehicles carrying cargo on top should watch for these signs. The sign is not a speed limit, since speed limits are posted on rectangular regulatory signs. Narrow bridges have their own warning sign, and exit distances appear on green guide signs. Check the height early so you have room to turn off safely.

3. 3. How should you respond when a yellow merge warning appears?

   
   1. Assume your lane ends immediately and stop in the travel lane
   2. Expect other traffic may enter your lane and adjust speed or lane safely
   3. Accelerate without checking because merging traffic must always yield to you
   4. Turn at the next side street to avoid the joining roadway
   Show answer

   Expect other traffic may enter your lane and adjust speed or lane safely. A merge warning alerts you to traffic joining your lane, so cooperation is the useful response. Be ready to adjust speed and lane position while checking mirrors and surrounding vehicles. The sign does not automatically end your lane, authorize acceleration without observation, or require a turn onto another street. Leaving room and maintaining awareness gives the entering driver a safe path without creating a sudden conflict.

Source: the Oklahoma Driver Manual, Chapter 4: Signs, Signals and Markings. 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.