This term is used to describe the process by which approval procedures for rolling stock are simplified, through the mutual recognition of approvals and certificates in several countries. This is implemented through intergovernmental agreements that recognise the approvals issued by other safety authorities.

In a broader sense, cross acceptance also covers aspects such as simplified access to rail networks, and the mutually recognised approval of engine drivers or certification of maintenance facilities.

In international railway cooperation, various mutually recognised regulations and processes have already been developed. While the Technical Specifications for Interoperability (TSI) define long-term rules for approval tests as a top-down process, the Safety Authorities (NSA) have a bottom-up approach through cross acceptance to support the approval process quickly and effectively. Both will increase the competitiveness of rail.

Issuing approval itself remains a State act of the territorial authority, which approves rolling stock on the basis of foreign technical specifications that are consistent with national safety regulations.

Cross acceptance involves the systematic comparison of different national requirements and their description in comparable structures. Currently eight countries (Austria, Belgium, France, Germany, Italy, Luxembourg, the Netherlands, Switzerland) have already produced structured descriptions of their national requirements. Further countries are currently drawing up their data.

Individual points are classified and can then be examined for comparability. Equivalent requirements are classed as A, different requirements as C. If the examination has not yet been completed, the point is classed as B.

In the international examination, A points are checked only once and are mutually recognised. This significantly reduces the effort of examination. At the same time, A points are important indicators for the further development of TSI.

Cross acceptance is a method for simplifying the approval process of international projects quickly and sustainably, while maintaining safety at a consistent level. Between neighbouring countries and within European corridors, cross acceptance is of major importance. Switzerland has already concluded corresponding agreements with several European countries.

In addition to the approval of rolling stock, cross acceptance covers significant points such as aspects of simplified access to the network, mutually recognised approval of engine drivers and certification of maintenance facilities. Here too, Switzerland has already signed international agreements with some neighbouring countries. Further agreements are in preparation.