Safety Margins Flashcards
How is stopping distance defined?
The distance the car travels from the moment you realize you need to break to the moment the car fully stops
When do you need to increase stopping distance?
- in wet conditions, double the distance
- in icy conditions, 10x the distance
- in faster conditions e.g motorways
How to figure out thinking distance :
Take the speed you are driving at and convert to feet. E.g is driving at 40mph, you will travel 40ft thinking distance.
What is aquaplaning?
Aquaplaning is when the tyres of a vehicle lift off the road and skate along the surface of any water collecting on the surface, causing the steering to become light. This can come about during, or following, heavy rainfall, leaving lots of water on road surfaces.
If aquaplaning occurs:
- Ease your foot off the accelerator pedal
- Wait for your steering to feel normal again before you brake
How should you drive in foggy weather?
In foggy conditions, you should:
- Plan for more time in your journey
- Keep your speed down since you won’t be able to see as far ahead
- Increase the separation distance between you and the vehicle ahead of you
- Switch on your dipped headlights – in daylight too
- If you have fog lights, you must use them if visibility falls below 100 metres (328 feet). When the fog lifts, you must switch them off.
How should you reduce skidding risk in slippery conditions?
In order to reduce the risk of skidding in wet or icy conditions:
- Reduce your speed
- Drive in the highest gear you can effectively use
What is ABS?
Anti-lock braking systems (ABS) prevent skidding which is caused by excessive braking. Sensors tuned to the speed of the wheels sense when they are about to lock, and the system prevents the wheels from locking. This allows you to continue steering while you brake.
Stopping distance is not reduced by ABS because it simply prevents skidding caused by braking which is excessive for the road conditions. Therefore, ABS is less effective when:
The road surface is covered with water, as after heavy rain
You’re driving on a loose surface like gravel
What is ESC?
Electronic stability control (ESC), or Electronic Stability Program (ESP®) enables the driver to turn the vehicle as expected whilst keeping the vehicle under control, as long as the speed of the vehicle isn’t too fast for the given situation.
Even with ESC, there is a risk of losing control if the driver is going too quickly. It is still the role of the driver to ensure that they can stop in the distance ahead of them.
ESC combines the functionality of ABS and traction control systems, and its purpose is to prevent sideways skidding of the vehicle. Advantages include:
Its ability to activate when the vehicle is about to skid
Early detection of the risk of skidding, even before the driver begins braking
Comparison of the driver’s intended direction with the direction the vehicle actually goes
Selectively intervening with brakes to stabilise the vehicle
When entering a contra flow system , you should :
Upon entering a contraflow system:
- Slow down in good time
- Get in the appropriate lane, as advised by signs for certain exits or if you’re driving a wider vehicle
- Always maintain a safe separation distance from the vehicle ahead of you
