We use the IPDE (Identify, Predict, Decide, Execute) approach to driving to deal with potential and real hazards. IPDE defines the four steps involved.
Identify
The first step to good driving and avoiding collisions is to identify, well in advance, real and potential hazards.
From the thousands of objects in your field of vision, you must learn to filter out those that do not provide you with information relevant to the driving task. For instance, although a red neon sign attached to a restaurant may catch your eye, it's an unnecessary distraction because it's irrelevant to the driving task. You must search for real or potential hazards (such as traffic lights or children) and give them your immediate attention.
To use this information the hazard must be spotted in plenty of time. That's why your windows need to be clear.
Predict
Step two is to predict what will happen should you encounter a real or potential hazard.
Real hazards
For a real hazard, such as a red light, stop sign or a stopped vehicle, you simply predict whether or not the traffic light will change or the vehicle will remain stopped.
You usually see real hazards in plenty of time and will have few problems predicting what will happen. Although you may be scanning the road properly, a vehicle may suddenly stop right in front of you. You will then have to quickly predict what may happen in the next few seconds.
Potential hazard
Every vehicle you share the road with is a potential hazard. Be aware of where other drivers could go. Make your best prediction of what they're likely to do and keep revising this prediction as you move towards them. Pedestrians, cyclists or children on the side of the road are often potential hazards.
Predict the path of potential hazards. The vehicle may make a right turn. The child may run across the road.
The more often you practise predicting what may happen and what pedestrians and other drivers might do, the quicker you'll be able to make accurate predictions.
Decide
Step three is to decide exactly what you'll do to drive smoothly and deal with the hazard. This means planning your actions in detail and checking to see that the way is clear to proceed.
Real hazards
You may decide to simply brake gently or change lanes to avoid the hazard, or you may want to brake hard, release the brakes and steer.
Potential hazards
When you encounter a potential hazard, you may decide to take no action and continue to monitor the actions of other drivers, or you may decide to take action to avoid the other vehicles.
Consider the following steps before you take any action:
- Check that your chosen gate is still open.
- Check the surface condition of the roadway for braking.
- Check the shoulder and the ditch.
- Continue to watch the vehicle and decide whether you will take action to avoid it.
Execute
The final step, to execute, means to carry out your decision.
Executing some of your decisions will simply mean making a smooth stop at a traffic light.
Executing other decisions may involve using techniques for emergency driving.
To be good at executing your decisions, particularly emergency decisions, you need to practise in a safe situation, preferably with a trained instructor. Practice helps you overcome the panic that usually arises the first time you're in an emergency.
Practice makes perfect
When you begin practising the IPDE method you'll be slow and will probably think in words. As you practise, you'll become faster and begin to think in ideas and pictures. At this stage, you will be able to carry out the entire procedure rapidly. You can cut your reaction time by taking the time to practise the IPDE method. It may save your life.
Once you have been using IPDE for some time, much of your identifying, predicting, deciding and executing will be carried out instinctively.
You'll need to use IPDE more often in heavier traffic and when you are driving at higher speeds.
You'll find that your physical condition greatly affects your ability to handle IPDE. If you're tired or ill, you should reduce the IPDE load by travelling at reduced speeds. You can reduce the IPDE load by avoiding heavy traffic. You might also consider not driving.
Alcohol and other drugs make it very difficult to carry our the IPDE process. Distraction also prevents you from using the IPDE method as you are not identifying hazards as quickly as you would need to. Since IPDE is designed to prevent you from having collisions, it's not surprising that a large number of crashes are alcohol, distraction and drug related.