The interoperability regime provides for the possibility of an exemption to be granted to allow a specific project not to comply with particular standards.
The Railways (Interoperability) Regulations 2011 provide for derogations to be granted, at the discretion of the Secretary of State, for projects to introduce new, upgraded or renewed subsystems but these are only available in limited circumstances which can be summarised as:
projects at an advanced stage
gauge or energy incompatibility issues
network separation or isolation by sea or geography
economic viability issues
accident or natural disaster recovery
In some circumstances, other factors can allow exemptions for upgrade and renewal work, and in all cases, the Secretary of State must notify the European Commission.