A body built on a truck chassis, a minibus converted from a panel van or an ambulance are typical examples of multi-stage approval. The main manufacturer has the base vehicle approved; later manufacturers add the work of their own stage on top of those approvals.
Base, intermediate and final stages
In the base stage, the first manufacturer has the incomplete vehicle approved. In an intermediate stage, another manufacturer takes the vehicle a step further. In the final stage, the vehicle is ready for use and is expected to meet the requirements of its category as a whole.
Each manufacturer is responsible for the systems it adds or changes in its stage, and for their conformity of production. Approvals from earlier stages remain valid as long as they are not changed, and enter the new file as references.
Where a bodybuilder should start
The first step is to collect the approval documents of the base vehicle and the manufacturer's body-building instructions. These show the limits within which the vehicle can be completed, notably permitted masses, axle loads, centre of gravity and systems that must not be touched.
The second step is to identify which regulations the work affects. Masses and dimensions, the lighting layout, seats and safety-belt anchorages are often affected. Unaffected subjects rely on earlier approvals, so no unnecessary testing is done.
How it differs from whole-vehicle approval
In whole-vehicle approval a single manufacturer answers for the whole vehicle. In multi-stage approval responsibility is divided between stages, and the strength of the file depends on the flow of information between them. Up-to-date, complete documents from the base vehicle manufacturer are therefore decisive.
This article is a summary for orientation. For legal requirements, always refer to the official text in force and its amendments.
