Safety, load securing and passenger safety
The exam tests whether you can secure a trailer load against realistic forces and keep passengers safe inside the bus at the same time. Load securing questions are numerical: know the accelerations and the friction allowance.
What the load may do
Load securing is judged against the forces the load will actually see: 0.8 g forwards, 0.5 g rearwards and 0.5 g sideways (EN 12195-1). A 1,000 kg crate therefore needs 800 daN of restraint forwards.
Methods that count
- Positive fit - blocking, headboards, wheel chocks - is the most reliable and uses the structure rather than straps.
- Lashings: the lashing capacity (LC) is marked on the strap in daN; pre-tension (STF) and angle matter. A strap at 45° contributes only about 70 % of its rated force in the direction you need.
- Friction helps: steel on wood is around 0.3–0.4, smooth metal on smooth metal far less. Assume less friction than you hope for.
- Side walls and tarpaulins secure nothing unless they are rated for it.
Passenger safety inside the bus
- No passenger may ride in the trailer under any circumstances: no restraints, no exits, no protection.
- Luggage must be behind rated partitions or in closed lockers; a 20 kg case becomes a 160 kg missile at 0.8 g.
- Keep emergency exits, aisles and door areas clear, and check that break-glass hammers and the roof hatch are present and unobstructed.
- Standing passengers are permitted only where the bus is approved for them; a coach on long-distance work with a trailer normally carries seated, belted passengers only.
- Seat belts must be worn where fitted, and the driver is responsible for briefing passengers.
Worked example
A 1,000 kg crate sits on a wooden trailer floor, μ ≈ 0.3. Forward force = 0.8 × 1,000 = 800 daN. Friction supplies 0.3 × 1,000 = 300 daN. The remaining 500 daN must come from lashings. One strap with LC 1,600 daN passed over the crate at about 45° delivers roughly 1,600 × 0.7 = 1,120 daN effective - comfortably more than 500 daN, but only if the anchor points are rated and the strap is tensioned against the load, not against the tarpaulin.
Traps
- Counting a strap's full LC without allowing for the angle.
- Securing only downwards, with no restraint against forward movement.
- Leaving a heavy item loose because the trailer is full.
- Forgetting to check the exits after loading luggage.