Since its opening the only change of the route of the line took place in early October 1977 with the deviation of the line with the relocation of the station at Les Halles. During the excavation of the enormous Les Halles complex the station of Les Halles was relocated about ten metres further east to allow a shorter connection to Châtelet – Les Halles RER station. For this, three hundred and thirty meters of tunnel were built to join the old route. The changeover took place on three consecutive nights from 10 pm on Friday, 30 September 1977 to the beginning of services on Monday, 3 October. On the first night, the new track 2 was connected, on the second night, the new track 1 was built and on the last night it was connected.