In the case where Regulation (EU) No 402/2013 applies, its Article 4(2) sets criteria for assessing the significance of a change that should be analysed by the proposer. The proposer can take its decision on the significance of the safety-related change based on only one or some of those criteria. But it shall keep adequate documentation to justify his decision.
The application of the above criteria can only be done by expert judgement having regard to the particular context of the project.
The question on the significance of a safety-related change does not release the railway company from its obligation to perform a proper risk assessment in order to demonstrate that the level of safety is maintained or even improved, e.g. by the implementation of existing or new risk control measures. Even if the risk assessment process in Annex I of Regulation (EU) No 402/2013 does not apply, the railway company must still have a risk assessment procedure in place, as part of its safety management system, to identify and manage appropriately the risks related to its activities.
The examples listed in the question above are all changes with an impact on safety for which the risks are to be evaluated systematically in accordance with the risk assessment procedures set in the safety management system of the railway company. When the change is significant, in addition to the risk assessment which is to be done by the railway company, an independent assessment body which fulfils the requirements in Article 6 and Annex II of Regulation (EU) No 402/2013 must also be appointed to the project. Its role is to verify independently the correct application of the risk assessment process in Annex I of that Regulation.