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03 มิถุนายน 2555

Safety Margins Category (UK)

Theory Test - Safety Margins Category


Topics include:
  • Road Surfaces - being aware of different road surfaces and how they can affect the driving experience.
  • Skidding - how to prevent and deal with skidding whilst driving.
  • Weather Conditions - being aware how different weather conditions can affect driving and road safety.
  • Stopping Distances - knowing the distances required to stop a vehicle safely.

Again safety is the key theme. Add this to a fair dose of common sense and many of the questions answer themselves.

Facts to Know - Weather conditions

  • Braking distances on ice and in freezing conditions can be ten times the normal distance.
  • Overall stopping distances will be much longer when driving in wet conditions.
  • In windy conditions take extra care when passing cyclists and motorcyclists. Always allow them extra room.
  • After driving through flood water the first thing you should do is test your brakes. You should then go slowly while gently applying the brakes, as this will help to dry them.
  • In very hot weather the road surface can become soft. This can effect tyre grip and braking.
  • Side winds are most dangerous on an open stretch of road.
  • When driving on a motorway with surface spray use dipped headlights.
  • When driving on snow or ice use the highest gear possible, as this helps avoid wheelspin. When approaching a sharp bend in such conditions you should slow down and avoid sudden steering movements.
  • If your number plate, windows, lights or mirrors are covered in snow or ice you must clear them before staring a journey.
  • To correct a skid you should drive into it i.e. if the back of your vehicle slides to the right you should steer to the right.
  • Skidding is usually cause by driver error, driving too fast for the road conditions.
  • To control the speed of your car when driving down hill, select a low gear, as this makes use of the engine brake, and use the brakes carefully.
  • When parking facing downhill turn the wheels towards the kerb and put the handbrake firmly on.
  • You can tell you are driving on ice, and black ice, because your tyres make little noise and the steering becomes light.
  • To avoid a collision when entering a contraflow system you should switch to the correct lane in good time, reduce speed in good time and keep the correct separation distance.
  • When driving in fog use dipped headlights, allow more time for your journey, slow down.
  • When approaching a right-hand bend you should keep to the left as this will improve your view of the road ahead.

In wet conditions your car can aquaplane. This means the tyres have lifted off the surface of the road and are skating on the surface of the water. If your steering suddenly becomes very light, while driving on a wet road, this is a sign that your are aquaplaning. To correct it ease off the accelerator and allow the tyres to regain grip.
Anti-Lock Brakes

  • Prevent the wheels from locking which means the tyres are less likely to skid.
  • Allow a vehicle to be steered whilst under braking.
  • May not work as effectively when the road surface is loose or wet.
  • In an emergency apply them rapidly and firmly.
  • They will start to work just as the wheels are about to lock.

Stopping Distances

The diagram shows overall stopping distances (thinking distance plus braking distance).
Stopping Distances

DSA Theory Test Questions - Safety Margins
1You have just gone through deep water. To dry off the brakes you should

Mark one answer.

Knowledge and UnderstandingWater on the brakes will act as a lubricant, causing them to work less efficiently. Using the brakes lightly as you go along will dry them out.

accelerate and keep to a high speed for a short time go slowly while gently applying the brakes avoid using the brakes at all for a few miles stop for at least an hour to allow them time to dry
2You are overtaking a motorcyclist in strong winds. What should you do?

Mark one answer.

Knowledge and UnderstandingIt is easy for motorcyclists to be blown off course. Always give them plenty of room if you decide to overtake, especially in strong winds. Decide whether you need to overtake at all. Always check to the left as you pass.

Allow extra room Give a thank you wave Move back early Sound your horn
3You are travelling at 50mph on a good, dry road. What is your typical overall stopping distance?

Mark one answer.

Knowledge and UnderstandingEven in good conditions it will usually take you further than you think to stop. Don’t just learn the figures, make sure you understand how far the distance is.

36 metres (118 feet) 53 metres (175 feet) 75 metres (245 feet) 96 metres (315 feet)
4What is the most common cause of skidding?

Mark one answer.

Knowledge and UnderstandingA skid happens when the driver changes the speed or direction of their vehicle so suddenly that the tyres can't keep their grip on the road. Remember that the risk of skidding on wet or icy roads is much greater than in dry conditions.

Worn tyres Driver error Other vehicles Pedestrians
5You are following a vehicle at a safe distance on a wet road. Another driver overtakes you and pulls into the gap you have left. What should you do?

Mark one answer.

Knowledge and UnderstandingWet weather will affect the time it takes for you to stop and can affect your control. Your speed should allow you to stop safely and in good time. If another vehicle pulls into the gap you’ve left, ease back until you’ve regained your stopping distance.

Flash your headlights as a warning Try to overtake safely as soon as you can Drop back to regain a safe distance Stay close to the other vehicle until it moves on
6You are trying to move off on snow. You should use

Mark one answer.

Knowledge and UnderstandingIf you attempt to move off in a low gear, such as first, the engine will rev at a higher speed. This could cause the wheels to spin and dig further into the snow.

the lowest gear you can the highest gear you can a high engine speed the handbrake and footbrake together
7The main benefit of having four-wheel drive is to improve

Mark one answer.

Knowledge and UnderstandingBy driving all four wheels there is improved grip, but this does not replace the skills you need to drive safely. The extra grip helps road holding when travelling on slippery or uneven roads.

road holding fuel consumption stopping distances passenger comfort
8You are on a long, downhill slope. What should you do to help control the speed of your vehicle?

Mark one answer.

Knowledge and UnderstandingSelecting a low gear when travelling downhill will help you to control your speed. The engine will assist the brakes and help prevent your vehicle gathering speed.

Select neutral Select a lower gear Grip the handbrake firmly Apply the parking brake gently
9Anti-lock brakes may not work as effectively if the road surface is

Mark TWO answers.

Knowledge and UnderstandingPoor contact with the road surface could cause one or more of the tyres to lose grip on the road. This is more likely to happen when braking in poor weather conditions, when the road surface is uneven or has loose chippings.

dry loose wet good firm
10You are driving in heavy rain. Your steering suddenly becomes very light. You should

Mark one answer.

Knowledge and UnderstandingIf the steering becomes light in these conditions it is probably due to a film of water that has built up between your tyres and the road surface. Easing off the accelerator should allow your tyres to displace the film of water and they should then regain their grip on the road.

steer towards the side of the road apply gentle acceleration brake firmly to reduce speed ease off the accelerator
11Your overall stopping distance will be much longer when driving

Mark one answer.

Knowledge and UnderstandingExtra care should be taken in wet weather as, on wet roads, your stopping distance could be double that necessary for dry conditions.

in the rain in fog at night in strong winds
12You have driven though a flood. What is the first thing you should do?

Mark one answer.

Knowledge and UnderstandingBefore you test your brakes you must check for following traffic. If it is safe, gently apply the brakes to clear any water that may be covering the braking surfaces.

Stop and check the tyres Stop and dry the brakes Check your exhaust Test your brakes
13You are on a wet motorway with surface spray. You should use

Mark one answer.

Knowledge and UnderstandingWhen surface spray reduces visibility switch on your dipped headlights. This will help other road users to see you.

hazard flashers dipped headlights rear fog lights sidelights
14How can you tell when you are driving over black ice?

Mark one answer.

Knowledge and UnderstandingSometimes you may not be able to see that the road is icy. Black ice makes a road look damp. The signs that you’re travelling on black ice can be that the steering feels light and the noise from your tyres suddenly goes quiet.

It is easier to brake The noise from your tyres sounds louder You will see tyre tracks on the road Your steering feels light
15Travelling for long distances in neutral (known as coasting)

Mark one answer.

Knowledge and UnderstandingCoasting, is the term used when the clutch is held down, or the gear lever is in neutral, and the vehicle is allowed to freewheel. This reduces the driver’s control of the vehicle. When you coast, the engine can’t drive the wheels to pull you through a corner. Coasting also removes the assistance of engine braking that helps to slow the car.

improves the driver's control make steering easier reduces the driver's control uses more fuel

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