Following distance, parking and backing

Key points

1. The three second rule is the minimum; increase it at high speeds or in bad weather.

   Source: Handbook p. 79

   “The three-second following distance rule is the minimum recommended safest procedure to use. At high speeds or in bad weather you will need to increase your following distance.”
   Idaho Driver's Handbook, Handbook p. 79

2. When stopped behind a vehicle, leave room to see its rear tires touching the ground.

   Source: Handbook p. 71

   “leave enough distance between the vehicles to see the rear tires (where they touch the ground) of the vehicle in front of you.”
   Idaho Driver's Handbook, Handbook p. 71

3. Park parallel to and within 18 inches of the curb or road edge, facing the direction of traffic.

   Source: Handbook p. 80

   “you must park parallel to and within 18 inches of the curb or edge of the roadway, facing in the same direction as traffic on your side of the road.”
   Idaho Driver's Handbook, Handbook p. 80

4. Facing downhill, turn your front wheels sharply toward the curb or road edge; facing uphill, turn them sharply away from the curb.

   Source: Handbook p. 81

   “turn your front wheels (1) sharply toward and against the curb or edge of the road if you are facing downhill, or (2) if you are facing uphill, turn your wheels sharply away and against the curb”
   Idaho Driver's Handbook, Handbook p. 81

5. Do not park within 50 feet of railroad tracks or within 15 feet of a fire hydrant.

   Source: Handbook p. 81

   “Within 50 feet of railroad tracks On bridges or overpasses In front of a driveway Within 15 feet of a fire hydrant”
   Idaho Driver's Handbook, Handbook p. 81

6. Do not park within 20 feet of a crosswalk or within 30 feet of a stop sign, yield sign or traffic signal.

   Source: Handbook p. 81

   “Within 20 feet of a crosswalk Within 30 feet of a stop sign, yield sign, or traffic signal”
   Idaho Driver's Handbook, Handbook p. 81

7. Do not park on a freeway or where a sign or red painted curb prohibits it.

   Source: Handbook p. 81

   “On any controlled-access highway (freeway) Where prohibited by signs or a red-painted curb”
   Idaho Driver's Handbook, Handbook p. 81

8. Backing is always prohibited on freeways and other controlled access highways, including the shoulder.

   Source: Handbook p. 82

   “Backing is always prohibited on freeways, expressways, and other controlled-access highways, including the shoulder.”
   Idaho Driver's Handbook, Handbook p. 82

9. If you miss your exit on an interstate, never back up or turn around; go on to the next exit.

   Source: Handbook p. 82

   “If you have passed your exit on an interstate, never back or try to turn around; go on to the next exit.”
   Idaho Driver's Handbook, Handbook p. 82

Numbers to know

Recognize these signs

3 questions from the Idaho practice test

1. 1. What is Idaho's minimum recommended following-distance procedure?

   1. Use at least three seconds, adding more time at high speeds or in bad weather
   2. Keep exactly one second behind the vehicle ahead in all conditions
   3. Stay within one car length whenever traffic is moving
   4. Match the vehicle ahead's speed and ignore the road surface
   Show answer

   Use at least three seconds, adding more time at high speeds or in bad weather. The three-second rule gives a driver a practical minimum gap for reacting to a sudden stop. At higher speeds or in bad weather, the handbook calls for increasing that interval because traction and stopping conditions can worsen. The one-second and one-car-length choices remove needed reaction space, while matching speed alone says nothing about distance. Pick a fixed object, count after the lead vehicle passes it, and enlarge the gap when conditions become demanding.

2. 2. You passed your exit on an Idaho interstate. May you back up on the shoulder to reach it?

   1. Yes, if you turn on your hazard lights
   2. No, backing is always prohibited on freeways, including the shoulder
   3. Yes, if no traffic is close behind you
   4. Only during daylight hours
   Show answer

   No, backing is always prohibited on freeways, including the shoulder. Backing is always prohibited on freeways, expressways, and other controlled-access highways, and that includes the shoulder. If you pass your exit on an interstate, never back up or try to turn around; go on to the next exit. Hazard lights, light traffic, or daylight do not create an exception. Elsewhere, backing is allowed only when it can be done safely without interfering with other traffic. Missing an exit costs a few minutes, while backing on a freeway is illegal and dangerous.

3. 3. A car is following you too closely. What does Idaho's space-cushion advice tell you to do?

   1. Brake suddenly to warn the driver
   2. Speed up to get away from it
   3. Move onto the shoulder and stop
   4. Slow down and let it pass
   Show answer

   Slow down and let it pass. Idaho wants you to keep plenty of space around your car on all sides, staying in the middle of your lane with enough room ahead to stop or pass safely. When someone follows too closely, the handbook's answer is to slow down and let that car go by. Speeding up just moves the problem along at a higher speed, and braking suddenly invites a rear-end crash. Pulling onto the shoulder and stopping is not part of the advice. Once the tailgater passes, rebuild your space cushion.

Source: the Idaho Driver's Handbook, Traffic Laws & the Rules of the Road. 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.