 The importance of the station in the railway network was consolidated with the electrification of the Hamm–Hanover main line on 29 September 1968 and the introduction of the Intercity-Express connection between Cologne and Berlin in the 1990s, stopping in Bielefeld, with connections at regular-intervals with regional services.During the rebuilding of the central sections of the Bielefeld tramway underground, the underground Stadtbahn station was not built under the Hauptbahnhof for cost reasons.The Hauptbahnhof Stadtbahn station was instead built 150 m to the south-east and is connected to the station forecourt by a covered travelator (popularly known as "die Tüte"