Two suppliers Thales and Alstom who are competitors in the rest of the world are working collaboratively on one of the biggest signalling programmes we have ever seen. This is possible thanks to a common standard ERTMS which simplifies and minimizes interface discussions. The leadership and commitment of Rail Net Denmark (Banedanmark) to take responsibility for the overall system integration is very important for the success of the programme. It is not primarily the technology which makes the project challenging, but the migration from the legacy systems to brand new signalling equipment to be brought into operation without major traffic disruption. The outcome will be a high-performance signalling system providing huge benefits to the Danish Railway sector.