Safe Braking Distances Flashcards
6 cards from real LGV practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Safe Braking Distances flashcards as text
What is the overall stopping distance for a vehicle travelling at 60 mph in ideal conditions (thinking distance plus braking distance)?
Answer: 73 metres (240 feet)
At 60 mph, the thinking distance is approximately 18 metres and the braking distance approximately 55 metres, giving an overall stopping distance of around 73 metres (240 feet) in ideal conditions. For a loaded LGV, this will be significantly greater.
How does vehicle weight affect braking distance for an LGV?
Answer: Greater weight increases kinetic energy, requiring significantly longer distances to stop
Kinetic energy increases with mass. A fully loaded LGV has vastly more kinetic energy than a car at the same speed and requires proportionally greater braking distances. This is why LGV drivers must maintain much larger following distances.
What effect does a wet road surface have on braking distance?
Answer: It typically doubles the braking distance compared to a dry road
A wet road surface approximately doubles stopping distances because the water film between the tyre and road surface reduces friction (grip). LGV drivers must double their following distance in wet conditions.
What is 'thinking distance' in the context of stopping distance?
Answer: The distance the vehicle travels during the driver's reaction time before the brakes are applied
Thinking distance is the distance covered from the moment a driver perceives a hazard to the moment they begin to apply the brakes. At 60 mph, a driver travels approximately 18 metres during a typical reaction time of 0.67 seconds.
What is brake fade and how does it affect LGV braking?
Answer: Reduced braking efficiency caused by heat build-up in brake components — especially dangerous on long descents
Brake fade occurs when friction materials and brake drums or discs overheat, reducing their ability to generate friction. For LGVs on long descents, continuous brake application generates extreme heat. Engine braking and gear selection are essential to prevent brake fade.
What is the recommended following distance for an LGV at 60 mph on a dry motorway?
Answer: At least a 2-second gap — but significantly more due to the vehicle's weight and longer stopping distance
The 2-second rule gives a minimum for cars, but heavily loaded LGVs have far longer stopping distances. Professional LGV drivers are trained to maintain much greater gaps — often 4-6 seconds or more — because their stopping distances can be 2-3 times longer than cars.