A seemingly minor modification can require a major approval process on electric buses

During the development and production of a bus, even changes that may appear insignificant to outsiders can trigger serious technical and regulatory processes. This is particularly true of modern electric buses, where modifications affecting high-voltage systems often require not only engineering work but also an official type-approval procedure. An example from France clearly illustrates how complex the process behind a seemingly small safety improvement can be.

On July 1, the competent state transport and technical authority in the Occitanie region of southern France homologated a new electrical safety modification applied to Irizar electric buses. In the event of an anomaly, the new solution further strengthens the automatic disconnection of the high-voltage system, reducing potential electrical risks. It is important to note, however, that the modification was not a response to a previous fault or accident: it is purely a preventive development intended to further enhance an already high level of safety.

What is really interesting, however, is not the technical development itself, but the approval procedure that preceded it. Because the modification affects the vehicle’s high-voltage electrical system, it could not simply be installed on the buses concerned; it first had to undergo an official type-approval procedure. The reason is that, under the European Union’s type-approval system, a bus is not merely a collection of components, but an approved vehicle type. If a manufacturer carries out a modification that may affect the vehicle’s safety or other approved technical characteristics, it is obliged to notify the type-approval authority. The authority then decides whether an amendment to the existing type approval is sufficient, whether further tests are needed, or whether an entirely new type-approval procedure must be carried out. In other words, the introduction of such a modification is not ultimately decided by the manufacturer. Even if the technical solution is ready, its application to vehicles already in service also requires the approval of the type-approval authority.

DREAL Occitanie ultimately applied a so-called series approval procedure: it inspected a single representative prototype at Irizar’s plant in Spain, and after successful homologation the modification could be carried out on all buses of the same type operating in France. This avoided the need for each individual vehicle to undergo a separate approval procedure, significantly speeding up the implementation of the conversion while also ensuring that the buses did not have to be withdrawn from service for an extended period.

The approval covers 60 Irizar electric buses operating under Paris RATP’s Bus2025 programme and assigned to the Malakoff depot, as well as vehicles of the same type running in Marseille, Brest and Bayonne. The case is a good example of how, in the case of modern buses, even a seemingly minor safety modification can enter day-to-day operation only as the result of a substantial technical and regulatory process. While this level of scrutiny may seem time-consuming, it plays a fundamental role in ensuring that changes affecting passenger safety are implemented uniformly and under controlled conditions.