Finland is isolated from other railway networks in European countries. Therefore, ERTMS is not needed to ensure interoperability and Finland will not be in the first wave equipping its network with ERTMS. In most cases ERTMS L1 will be chosen for implementation. However, many challenges still exist. It may not be possible to interface ERTMS with currently used interlocking systems especially if route information to balises is directly obtained from the interlocking system. In some cases it will be necessary to replace interlockings or to postpone the implementation. In addition, it is important to develop engineering and operational rules in the early implementation phase. For practical reasons a pilot line will be required and its location and properties are currently being studied in Finland.