4.1 Defensive Driving, Following Distance & Stopping Distance

Even experienced drivers make mistakes. Equipment fails, the weather turns, and other people ignore the rules. Defensive driving means expecting those problems and leaving yourself the time and space to avoid them.

Defensive Driving Habits

• Keep good vision in front of and around your vehicle, and check mirrors often.
• Stay alert and prepared for the unexpected. Expect mistakes from other drivers.
• Keep your eyes on the road. Even a split-second look at a passenger or an object inside the car can be dangerous.
• Keep space around your vehicle so you can change lanes suddenly if needed. Know who is beside and behind you, not just in front.
• Watch for vehicles stopping, people getting out of parked cars and back-up lights ahead.
• Watch crosswalks closely and do not rely on signals, because others may ignore them.
• Take extra care near playgrounds, schoolyards and shopping centers, where children may be hidden.
• Remember that pedestrians, bicyclists and drivers may not hear you. One in five people of driving age is Deaf or hard of hearing.
• Right-of-way is something you give. Yielding to prevent a conflict is a core defensive skill.

Your Health and Physical Condition

Have your eyes checked every year or two, and fix any vision problem immediately. Never drive:

• After drinking alcohol
• After taking a prescription or over-the-counter medication that can cause drowsiness
• Under the influence of any drug
• When you are very tired
• When you are upset, since anger and depression lead to careless driving

Wear sunglasses on bright, sunny days.

Safe Following Distance

The Three-Second Rule

1. Pick a fixed object ahead, such as a sign post or a tree.
2. When the vehicle ahead passes it, count "one one-thousand, two one-thousand, three one-thousand."
3. If you reach the object before you finish counting to three, you are too close. Slow down and count again.

Three seconds is the minimum for good roads and moderate traffic. Count more whenever traffic allows.

Never cut in front of heavy equipment or tractor-trailers, since they need much more room to stop. Tailgating is illegal, it is the main cause of rear-end crashes, and the fine can be as high as $100. If someone tailgates you, change lanes or pull aside and let them pass.

Leave extra space for bad drivers and for:

• Rain, snow, ice or other poor weather or road conditions
• Blind or obstructed driveways and roads
• Drivers backing out of parking spaces or driveways
• Children playing near the road

Braking and Stopping

Reaction time is the time it takes to see a hazard, decide, and get your foot on the brake: about three-quarters of a second. The distance you travel in that time is the reaction distance. The distance you travel after the brakes engage is the braking distance. Together they make the total stopping distance.

These figures come from the AAA text the manual cites. They are educational examples: real distances grow on wet, slippery or uneven pavement, when going downhill, and in bigger, heavier vehicles. Large trucks may need twice the stopping distance of a passenger vehicle.

A Worked Comparison

Speed matters more than most new drivers expect. Going from 50 to 60 mph is only 20 percent faster, but the sample stopping distance rises from about 215 to about 292 feet, roughly 36 percent farther. That extra 77 feet can be the length of a crosswalk and the car waiting behind it.

Braking Tips

• Brake early and gently when preparing to stop or turn. It warns drivers, bicyclists and pedestrians behind you.
• Do not ride your brakes: never rest a foot on the pedal while driving.
• If your vehicle has antilock brakes, never pump them. Press firmly and steer.
• Vehicles are more likely to leave the road on a curve, so slow down before curves and wherever you cannot see clearly ahead.

Following-Distance Scenarios

1. Behind a dump truck on a state highway: keep at least ten seconds, and never cut in front of it.
2. A tailgater rides your bumper on a two-lane road: pull to the side where it is safe and let them pass rather than braking to warn them.
3. Rain begins on the highway: add seconds to your three-second count right away, because stopping distances grow on wet pavement.

Putting It Together

A defensive driver scans far ahead, keeps at least a three-second cushion (more behind motorcycles, heavy equipment and in bad weather), brakes early, and never assumes another driver will yield. These habits also prevent the at-fault crashes that become surchargeable events on your record (Chapter 5).