Iowa · Handbook chapter 8 · 5 min read

Braking, stopping distances and the 3- to 4-second rule, required stops, ABS, Iowa's default speed limits, steering and backing, turn signals at 100 and 300 feet, turns on red, lane changes, passing rules, defensive driving, tailgaters, headlights, the horn and hazard lights.

Why this chapter matters

This chapter holds most of the numbers on the test: stopping distances, following distances, speed limits and signaling distances. Learn them as rules you will actually use.

Stopping

• Stopping distance = reaction distance + braking distance. At 20 mph it is about 69 feet; at 40 mph about 189 feet; at 60 mph about 359 feet. At 60 mph you travel about three times as far before stopping as at 30 mph.
• Loose gravel, snow, ice and even dry pavement can make you skid if you brake too hard.
• To warn drivers behind you, tap the brake pedal three or four times before slowing where they might not expect it.

Following distance

• Use the 3- to 4-second rule: when the car ahead passes a landmark, count; you should not reach the landmark before you count to three.
• Beginners should keep at least three seconds. At 40 mph, keep four to five seconds. On slippery roads, or when the vehicle ahead blocks your view, keep six seconds or more.

Required stops

Always stop: at every stop sign; before crossing a sidewalk when leaving a driveway or alley; when entering a public road from a private drive or parking lot; when an officer or flagger tells you to; at a flashing red light; at every red light, even where right on red is allowed; and when a person with a white cane or guide dog is in or near your path.

ABS

With antilock brakes, in an emergency press the pedal as hard as you can and keep pressing. The pedal may push back; do not let up.

Speed

• A posted limit is the maximum under ideal conditions.
• When no limit is posted: 20 mph in a business district; 25 mph in a residential or school district; 45 mph in a suburban district and for any vehicle towing another; 50 mph on unsurfaced secondary roads from sunset to sunrise; 60 mph on primary roads, urban interstates and secondary roads in daylight; 70 mph on rural interstates.
• Driving too slowly is also dangerous. The interstate minimum is 40 mph.

Steering and backing

• Hold the wheel at 9 and 3 o'clock, or a little lower at 7 and 5. Turn with the hand-over-hand or push-pull method, and never let the wheel spin back through your fingers.
• Look well down the road. When backing, turn your body and look over your right shoulder through the rear window; do not rely on mirrors or cameras alone. Back slowly.

Turning and signals

• Plan turns early. Do not cut corners or swing wide.
• Signal at least 100 feet before turning where the limit is 45 mph or less, and at least 300 feet where it is over 45 mph. Signal before you slow down, but not so early that someone thinks you are turning into an earlier driveway.
• Right on red is allowed after a full stop, yielding to all traffic, unless a "No turn on red" sign is posted. A left on red is allowed from a one-way street onto another one-way street.
• Three-point turns are risky; going around the block or to the next intersection is better.

Changing lanes

Change one lane at a time. Signal, check your mirrors, look over your shoulder at your blind spot while keeping the wheel straight, check the far lane for anyone moving into the same space, and keep your speed.

Passing

• Pass only where signs and markings allow and when there is room. Pass one vehicle at a time.
• Return to your lane when you can see the front of the passed car in your rearview mirror.
• Passing is illegal near the top of a hill, on a curve where you cannot see, within 100 feet of an intersection, a railroad crossing, or a signed narrow bridge, viaduct or tunnel, on the right, and when oncoming traffic is too close.

Defensive driving

About 94 percent of serious crashes come from drivers' choices or errors. Scan 20 to 30 seconds ahead, do not count on others to do the right thing, keep your following distance, match speed to conditions, always keep an escape route and stay focused.

If someone tailgates you, move slightly right, signal early, slow down to encourage them to pass and, if needed, pull out of traffic.

Headlights, horn and hazard lights

• Iowa requires headlights from sunset to sunrise and whenever you cannot see 500 feet ahead. A good habit: wipers on, headlights on.
• Use the horn to warn others, for example when a pedestrian may step into your lane or you cannot see around a corner.
• If you break down, get off the road if you can and turn on your hazard lights. Do not stop just over a hill or around a curve.