Safety Margins - Vehicle Control Flashcards
Stopping distances
Distance your vehicle takes to stop from when you think about braking, and react to it
20mph -> 20 x 2 = 40 feet
30mph -> 30 x 2.5 = 75 feet
40mph -> 40 x 3 = 120 feet
50mph -> 50 x 3.5 = 175 feet
60mph -> 60 x 4 = 240 feet
70mph -> 70 x 4.5 = 315 feet
Don’t forget just add 0.5 for every extra 10mph of speed
Another way to work out stopping distances
Take the first digit of the mph
1) 60mph would be 6
2) Divide it by 2 = 3
3) Add 1 = 4
4) 60 x 4 = 240
1) 40mph would be 4
2) Divide it by 2 = 2
3) Add 1 = 3
4) 40 x 3 = 120
Thinking distance increases by 3 metres for every 10mph faster you are travelling. That’s around 10 feet.
If you can work out the stopping distance and remember that when travelling at 20mph the thinking distance is 20 feet, you can then work out the braking distance by taking the thinking distance from the stopping distance
20mph, 6m TD, 6m BD = 40 feet (12metres)
30mph, 9m TD, 14m BD = 75 feet (23 metres)
40mph, 12m TD, 24m BD = 118 feet (36 metres)
50mph, 15m TD, 38m BD = 175 feet (53 metres)
60mph, 18m TD, 55m BD = 240 feet (73 metres)
70mph, 21m TD, 75m BD = 315 feet (96 metres)
4x4 Vehicles
The engine drives all 4 wheels
You get improved road holding as there is extra grip
Steep downhill gradients
Select a lower gear to make use of engine braking and prevent your wheel brakes from overheating
Engine braking
When you select a lower, gear, there is less drive from the engine so the vehicle starts to slow down
Parking with the wheels facing the kerb
If you are facing downhill, select reverse gear, as this will prevent the car from moving should the handbrake fail
If you are facing uphill, select 1st gear
Coasting
Driving with the clutch in or in neutral
Anti-lock braking systems
Are safety features that help to prevent your wheels from locking up when maximum pressure is applied to the brakes
You should NOT release the brake pedal until you have come to a complete stop
It works by rapidly applying and releasing the brakes - this will allow you to continue to steer
Skidding
If you find your car starts to skid it is best to steer into it. For example if you slide to the left steer left.
DO NOT brake
At contraflow systems…
Reduce your speed
Ensure you are in the correct lane
Keep the correct separation distance
If the vehicle behind is too close
Increase the gap between you and the vehicle in front
Built up areas with speed humps
Slow down
Watch out for pedestrians
Maintain a reduced speed
Sharp bends with reduced visibility
Slow down
Proceed with caution
Triangular sign with line bending right
