The List of regional rail lines in North Rhine-Westphalia provides a list of all Regional-Express and Regionalbahn railway lines in North Rhine-Westphalia. The passenger rail service in North Rhine-Westphalia is one of the densest train services in Germany, comprising 100 million train kilometers and is mainly operated on an integrated timetable, which has been in effect since 1998 with the introduction its current version, known as 1998 .