Warning, Guide and Service Signs

Key points

1. Warning signs are yellow with black lettering or symbols, and most are diamond shaped.

   Source: Handbook p. 9

   “Warning signs are yellow with black lettering or symbols and most are diamond-shaped.”
   Iowa Driver's Manual, Handbook p. 9

2. At a hill sign, check your brakes before going down the hill.

   Source: Handbook p. 9

   “You should check your brakes before going down the hill.”
   Iowa Driver's Manual, Handbook p. 9

3. At a deer crossing sign, slow down and watch carefully.

   Source: Handbook p. 9

   “There may be deer trying to cross the roadway in the area. Slow down and watch carefully.”
   Iowa Driver's Manual, Handbook p. 9

4. A lane ends sign means two lanes will become one, and traffic must yield when merging.

   Source: Handbook p. 9

   “Two lanes of traffic will soon become one lane of traffic. Traffic must yield when merging.”
   Iowa Driver's Manual, Handbook p. 9

5. A reflective orange triangle on the back of a vehicle means it travels 35 mph or less.

   Source: Handbook p. 11

   “A reflective orange triangle on the rear of a vehicle means it is traveling 35 mph or less.”
   Iowa Driver's Manual, Handbook p. 11

6. Mile markers help you figure the distance to your exit and give your exact location in an emergency.

   Source: Handbook p. 11

   “They can be used to calculate how far you are from your exit or destination and give your exact location in an emergency.”
   Iowa Driver's Manual, Handbook p. 11

7. Service signs show rest areas, fuel stations, campgrounds or hospitals.

   Source: Handbook p. 11

   “Service signs show the location of various services; such as rest areas, fuel stations, campgrounds, or hospitals.”
   Iowa Driver's Manual, Handbook p. 11

Numbers to know

Recognize these signs

3 questions from the Iowa practice test

1. 1. What color are most Iowa warning signs?

   1. Blue
   2. Yellow
   3. White
   4. Brown
   Show answer

   Yellow. Most Iowa warning signs are yellow with black lettering or symbols, and most have a diamond shape. Blue signs point to traveler services, white signs provide regulatory information, and brown signs identify recreation or cultural points of interest. Warning color is an early cue that a special situation or hazard is ahead, but the symbol or wording supplies the exact message. Reduce speed and scan for the condition shown, especially near curves, crossings, merging traffic, or slippery pavement. Color helps classify the sign before its detailed instruction is read.

2. 2. What do mile markers on an Iowa interstate show?

   1. Miles remaining to the next rest area
   2. Miles to the state capital
   3. Miles until the speed limit changes
   4. Miles from where the interstate route entered the state
   Show answer

   Miles from where the interstate route entered the state. Mile markers count the miles from the point where the interstate route entered the state you are traveling in. Drivers can use them to work out how far they are from an exit or destination, and they give your exact location in an emergency. That last use matters if you need help: Iowa's stranded-in-snow advice tells you to look for exit numbers, mileposts, crossroads, or landmarks to guide crews. Rest area locations appear on service signs instead.

3. 3. What does Iowa's Hill warning sign tell a driver to do?

   1. Shift into neutral
   2. Check your brakes before going down the hill
   3. Turn off the engine to save fuel
   4. Increase speed to climb
   Show answer

   Check your brakes before going down the hill. The Hill sign warns all vehicles that the road ahead goes down a hill, and the manual says you should check your brakes before going down it. The warning applies to all vehicles, not just trucks. Shifting into neutral or turning off the engine is not the advice the manual gives, and the sign is about a descent, not a climb.

Source: the Iowa Driver's Manual, Chapter 2: Warning, Guide and Service Signs. 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.