The second major difficulty in the construction of the Wientallinie represented the elaborate reconstruction of the station Hauptzollamt, which alone cost over eight million Austrian crowns. This was done while maintaining the rail traffic to the Vienna Main Customs Office and the wholesale market hall and was associated with time-consuming provisional. The station was originally in high altitude and had to be lowered by 6.82 meters for the Stadtbahn, because both adjacent new lines were Tiefbahnen. This project was made even more difficult by the existing connection to the Praterstern, which in turn remained an elevated railway.