If there is a gap between the load and the headboard, the load can shift forward under braking, risking the life of the driver, other road users and people involved in unloading.
The headboard should be sufficiently robust to resist movement of the load.
Wherever possible, trailers should be filled tight to the front headboard or bulkhead. Never the less it is important to consider the distribution of weight of the load on the vehicles axles.
If it is not possible to fill the load to the front bulkhead, intermediate bulkheads or other methods of restraint should be used, again considering the distribution of weight on the vehicles axles.