DTT HGV Passenger Safety and Air Brakes 2 — Questions and Answers
Question 1: What happens to an air-braked vehicle if it runs out of compressed air pressure while driving?
- The spring brakes apply automatically — bringing the vehicle to an emergency stop (Correct answer)
- The vehicle gradually loses braking ability until it cannot stop
- The driver is warned by alarms but braking continues until the vehicle stops
- Air brakes switch to hydraulic mode as a backup
Correct answer: The spring brakes apply automatically — bringing the vehicle to an emergency stop
When air pressure drops to a critical level, the spring brakes apply automatically. This is a safety feature — the vehicle stops automatically rather than losing braking capability. The driver will experience a sudden stop.
Question 2: How should a bus driver manage standing passengers when braking?
- Brake smoothly and progressively to allow standing passengers to brace — avoid sudden stops that could cause them to fall (Correct answer)
- Standing passengers hold responsibility for their own safety — drive normally
- Apply a horn signal before braking to warn standing passengers
- Require all standing passengers to face forward at all times
Correct answer: Brake smoothly and progressively to allow standing passengers to brace — avoid sudden stops that could cause them to fall
Standing passengers are vulnerable to sudden braking. A professional bus driver uses smooth, progressive braking to minimise sudden forces on passengers who cannot brace as effectively as seated occupants.
Question 3: What is the purpose of a 'brake test' when taking over an air-braked vehicle?
- To confirm that the service brakes, spring brakes, and warning systems all function correctly before driving on public roads (Correct answer)
- A legal requirement for vehicles over 7.5 tonnes before each journey
- To warm the brake pads before heavy braking situations
- To check that the anti-lock braking system (ABS) is working
Correct answer: To confirm that the service brakes, spring brakes, and warning systems all function correctly before driving on public roads
A static brake test checks that air pressure builds correctly, warning lights extinguish at correct pressure, and that both service and spring brakes function. It must be done before every journey in an air-braked vehicle.
Question 4: What should a bus driver do if a passenger becomes seriously ill during a journey?
- Stop the vehicle safely, call emergency services, administer first aid if trained, and keep passengers calm until help arrives (Correct answer)
- Complete the route and call an ambulance on arrival at the terminus
- Ask other passengers to assist — the driver must focus on driving
- Use the bus radio to report only — do not deviate from the route
Correct answer: Stop the vehicle safely, call emergency services, administer first aid if trained, and keep passengers calm until help arrives
A driver has a duty of care to all passengers. In a medical emergency, stop safely, call 999, administer basic first aid if trained, and protect the patient and other passengers while awaiting emergency services.
Question 5: What are the brake fade risks specific to heavily loaded trucks descending steep hills?
- Continuous heavy braking overheats brake drums — brake fade reduces stopping power, potentially causing loss of control (Correct answer)
- Air brakes are immune to fade — only hydraulic brakes fade
- Brake fade only occurs on vehicles without ABS
- Fade only affects the trailer brakes — the tractor brakes are unaffected
Correct answer: Continuous heavy braking overheats brake drums — brake fade reduces stopping power, potentially causing loss of control
Even air brakes can fade if brake drums overheat through continuous heavy use on long descents. Experienced truck drivers use engine braking (low gears) on long descents to protect the brakes.
Question 6: What is the 'dead man's switch' or driver incapacitation system on modern buses?
- A safety system that applies the brakes and stops the bus if the driver becomes incapacitated and fails to respond to prompts (Correct answer)
- A speed control system that prevents the bus from exceeding the limit
- A door interlock that prevents doors opening while the bus is moving
- An automatic emergency call system that contacts the depot
Correct answer: A safety system that applies the brakes and stops the bus if the driver becomes incapacitated and fails to respond to prompts
Driver incapacitation systems detect if the driver is unresponsive (through foot pedal inactivity or other sensors) and automatically bring the vehicle to a safe stop — preventing runaway in the event of a sudden medical event.
DTT HGV Passenger Safety and Air Brakes 2
What happens to an air-braked vehicle if it runs out of compressed air pressure while driving?