The holder of a Part B certificate shall inform the Intergovernmental Commission without delay and propose appropriate modifications to its Part B certificate whenever it proposes to alter substantially the type or extent of its operations or where any proposed changes referred to in Article 51 would necessitate modifications to the certificate.

In proposing any introduction of a new element into the railway system or the modification of an existing element of that system the holder of a Part B certificate shall ensure that such new elements or modifications would not reduce the overall level of safety and, where reasonably practicable, would improve it.

The Intergovernmental Commission’s procedures for considering such proposals will be the same as for considering an application for a Part B certificate. The period of validity of the Part B certificate shall not be affected by the approval of any such proposals unless the decision of the Intergovernmental Commission indicates otherwise and the Part B certificate is modified accordingly.