Safe Braking Distances Flashcards

What is the purpose of an Electronic Stability Programme (ESP) on a modern LGV?

Answer: It detects and corrects oversteer or understeer by selectively applying brakes to individual wheels

ESP detects instability (oversteer, understeer, or rollover risk) and automatically applies braking to individual wheels to correct the vehicle's path. For LGVs, it also includes roll stability control to prevent tipping on bends.

An LGV driver is carrying a load of loose granular material (aggregate). How does this affect braking?

Answer: The load can shift during braking, affecting stability and requiring progressive braking and reduced speed

Loose granular loads shift under braking and acceleration, moving the vehicle's centre of gravity. This can cause the vehicle to become unstable. Progressive braking reduces the rate of load shift, and lower speeds reduce the severity of any instability.

How should an LGV driver adjust their braking on a road that may have ice only in certain areas (patchy ice)?

Answer: Maintain reduced speed throughout, apply brakes very progressively, and be especially cautious on bridges, shaded areas, and under trees

Patchy ice is unpredictable. Black ice is invisible. Drivers should maintain reduced speed throughout sections where ice may occur. Bridges, shaded areas, and points where trees overhang the road are most prone to ice formation.

What is the role of the air brake system's trailer brake valve (trailer hand brake) in emergency situations?

Answer: It can be used to apply trailer brakes independently to help control a jack-knifing tendency in certain situations

The trailer brake valve (hand control valve) can be used carefully to apply trailer brakes independently. In certain situations, it may help control trailer swing or jack-knife tendency, but improper use can worsen the situation. It is also used for trailer parking.

What stopping distance should an LGV driver aim to maintain in fog?

Answer: Be able to stop within the distance they can see — if visibility is 20 metres, stopping distance must be within 20 metres

In fog, the driver must be able to stop within the visible distance. If visibility is 20 metres, speed must be reduced so that stopping is possible within 20 metres. Driving faster than visibility allows is sometimes called 'overdriving your headlights'.

What is a 'runaway vehicle' trap (sand or gravel escape lane) used for on a steep descent?

Answer: An emergency escape route for a vehicle with failed brakes — designed to stop the vehicle safely

Escape lanes (typically filled with loose sand, gravel, or aggregate) are positioned on steep descents to bring runaway vehicles to a stop safely if their brakes have failed. LGV drivers must know the location of escape lanes on routes with significant gradients.