What type of wheel chocks must be carried on a transport unit carrying Class 1 explosives under ADR 8.1.5?

1. Wooden blocks taken from old pallets without sizing check
2. Chocks are required only when parking on gradients over 45 degrees
3. At least one wheel chock per vehicle of a size suitable to the maximum mass of the vehicle and the diameter of the wheel
4. No wheel chocks are needed if the driver leaves the engine running