Unit: Eight Topic: L7
(Please Listen to Narration or read the Paragraphs below )

L7. Defensive driving, space cushions, ahead.

Many drivers don't see ahead as well as they should because they follow other vehicles too closely, and the vehicle ahead blocks their view of the road. If you can't see what is going on ahead in your lane, you should either take action to change to a lane or position where you can, or increase the space cushion in front of your vehicle.

Defensive drivers keep a safe following distance so they can see better. The more space you allow between your vehicle and the one ahead, the more time you will have to see a hazard or accident down the road. You will have more time to stop, turn, or otherwise avoid the hazard.

Keep enough space between your vehicle and the vehicle ahead so that you will have a bigger picture of what lies down the road. Steering to avoid trouble will be easier. Travel in the center of your lane instead of hugging one side or the other to let you see ahead. 

Most rear-end accidents are caused by following too closely. It is important to keep a sufficient distance behind other cars: (a) so as to be able to stop and maneuver in an emergency, and (b) provide good visibility of the roadway ahead.

A rule of thumb for a safe following distance under good driving conditions is the "three-second rule." When the vehicle ahead of you passes a certain point, such as a sign or road marking, count "one-thousand-one, one-thousand-two, one-thousand-three." This takes about three seconds. If you pass the point on the road before you finish counting, you are following too closely. You should adjust your speed so that you do not arrive at the point until after you are finished counting. At faster speeds, the distance should be greater.

In normal traffic under good weather conditions a time gap of 3 seconds between you and the car ahead of you works well. For example, at 30 miles per hour you cover 44 feet per second, or about 5 car lengths in two seconds. A 3-second gap allows you to see around the car ahead, to quickly change lanes, or to stop if the car ahead suddenly brakes.

However, if your vision is blocked by a vehicle such as a van, SUV, or large truck which prevents you from observing a collision or blocked lane ahead, you will need to increase your following distance to at least 4 seconds. Adverse roadway or weather conditions such as a rough road, rain, or snow also indicate a need for larger gaps up to 6 seconds or more, to allow you room and time to respond.

The 3-second following distance works well if you have to stop suddenly because the driver ahead brakes to a stop. However, at highway speeds, a 3-second following distance will not give you enough time to stop if the road ahead is suddenly blocked by a collision or a vehicle stopped in your lane. For example, at 55 miles per hour, you would need nearly 4 to 5 seconds to stop. Because of this, your position in traffic should be based on the availability of escape routes, which will be discussed later.

There are a number of situations where you will need more than a 3-second cushion. Give yourself a "4-second or more" cushion: (a) when you are being tailgated, (b) on slippery roads because you need more room to stop your vehicle, (c) when visibility is reduced, (d) when following motorcycles so as to avoid hitting a fallen cyclist, (e) when the driver behind you wants to pass, you should slow down to allow room in front of your vehicle so the driver will have space to move into, and (f) when pulling a trailer or carrying a heavy load because the extra weight makes it harder to stop.

You should also give yourself a 4-second or more cushion: (a) when following large vehicles that block the view ahead because you need the extra room to see around the vehicle and to the sides, (b) when you encounter a bus, school bus, or vehicle carrying hazardous materials near a railroad track because they must stop at railroad crossings-- you should expect that they will stop and slow down early to allow plenty of room, (c) when merging onto freeways, (d) when following a school bus, and (e) when following drivers that appear to be confused, distracted, or drunk.