Looking Not Seeing











There are many defensive driving topics covered in most driving courses, and it is not our intent to re-invent the wheel here. However these are some subjects I feel all instructors should put major emphasis on. All operators of large vehicles need to know and understand these foundation items in order to be safe and survive various changing traffic conditions.

These are important techniques that should be included in every large vehicle driving course, and the instructor must ensure their students understand and live each one in order to survive amongst todays agressive drivers.

Vision Habits look for

I think we can all agree when it comes to driving or operating a large vehicle in todays world, vision habits play the most important part in being a defensive driver and staying safe.

This is one of the most important things to be passed on to new drivers of large vehicles.

People today tend to look, but not look at. They fail to see the hazards present in their traffic picture.

Anytime you see skid marks on the pavement it means someone spotted a hazard - Too Late!

Eye Lead Time

Most defensive driving courses will suggest an operator should be scanning the traffic picture ahead for anything that will concern them in the next twelve to fifteen seconds in city and urban areas

Out on the highway twenty seconds, or as far as you can see.

While doing this, the operator is required to scan their mirrors every three to five seconds.

Peripheral vision

Wikipedia's definition of Peripheral vision is a part of vision that occurs outside the very center of gaze. This is what we can see almost off the the side at 90 degrees. Or to put it another way, we have almost 180 degrees of vision if we have good eye sight .

Most people don't use it or don't use it fully, especially when driving. During my years of training drivers of large vehicles, I found you have to coach and encourage people to make use of side vision commonly called peripheral vision. If you concentrate on using peripheral vision, while walking, driving and most any time, you will find it becomes almost automatic.

With practise you can pick up movement very quickly off to the side. You will detect developing hazards much more quickly and give yourself that extra time to react or make an adjustment. It can certainly help avoid collisions and is worthwhile for the instruct to spend some time with students to learn how to use peripheral vision constantly and effectively.

Time Interval Formula

This is used to determine a safe following distance for large trucks and buses.

1 second for each 10 feet of vehicle length.

For example: A 40 ft vehicle requires 4 seconds of following distance from the vehicle in front.

Here's how it works.

time interval formula

Pick an object up ahead, a bush, overpass, sign, and begin counting when the vehicle in front passes the object.

One thousand one, one thousand two...

When your vehicle passes the object stop counting.

If you have reached one thousand four or greater you can get stopped in an emergency.

If you pass the object at one thousand two or one thousand three you are following much too close and would never be able to stop in time.

Works for any vehicle at any speed.



Standard Collision Prevention Formula

Recognize The Hazard

Understand the Defence

Act In Time

Stopping Distance For Large Vehicles


Reaction Time

Brake Lag

Braking Distance

Stopping distances for large vehicles depends on the factors listed above. You need to see a hazard (Perception) up ahead and determine if you need to do somethng. If an undesirable situation has developed you need to brake quickly (Reaction). Everyone has at least a 3/4 of a second reaction time. That is how far your unit travels from the time you realize you have to stop until your foot contacts the brake pedal. Large vehicles usually have air brakes, and that adds an additional factor (Brake Lag). That is how long it takes for the air to activated the brake shoes against the brake drums after you press the brake pedal. This is 4/10s of a second. Then there is the final Braking Distance for the type of vehicle you are driving. All of this is happening in micro seconds and you are covering a lot of ground while it is going on.

This chart illustrates the above items:

brake chart







These figures are for a 40ft transit style coach.







You can see that Reaction Time and Brake Lag contribute significently to braking distance and are factors the instructor needs to ensure all drivers are aware of. It emphasizes the importance of above average visual habits.






Avoiding Collisions

Definition: Defensive Driving - Preventable Collision

defensive driving definition



Defensive Driving covers a lot of ground when you think about it. You are driving for others as well as yourself.






preventable collision definition



Preventable Collision usually means the operator did everything they could within reason to avoid it.



However avoiding all collisions should be the goal. Even if you are involved in a Non-Preventable collision it affects your life. You still have to file reports, may have to go to court, you could be injured and you are subject to stress wondering what the outcome will be.



Remember: Any collision has the potential to change your and your family's life forever.

These are two definitions the instructor should make sure that each and every operator understands and memorizes.





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