Planning and construction

The Federal Transport Policy Program (Verkehrspolitische Programm der Bundesregierung) of 1967 (known as the Leber Plan), according to DB information, inspired the planning and financing of the Frankfurt Airport railway.^[5] In June 1968, the railway division (Bundesbahndirektion) of Frankfurt am Main received planning approval for the airport railway.^[2] A 7.5 kilometre-long new line with an approximately 1.5 kilometre-long tunnel was planned.^[6] In total, 17 new bridges were planned along the line.^[3]

On 18 April 1969, Deutsche Bundesbahn and the FAG airport company concluded a financing agreement for connecting the airport to the railway network.^[2]

At the end of 1971, Deutsche Bundesbahn announced that it was bringing forward the opening of the airport railway, at least for the section between the Hauptbahnhof and the airport, from autumn 1972 to spring 1972. The total length of the new line between the junction at Frankfurt Sportfeld (now Frankfurt Stadion) and the junction at Kelsterbach, was 7.5 km.^[7]

According to the planning status of 1971, two trains per hour and direction would operate and, after the upgrade of S-Bahn tracks towards Frankfurt, operations would be run at 10-minute intervals. Long-distance trains would not normally be routed through the airport.^[2] The estimated cost of the project was estimated to be DM 94 million in 1968 and around DM 100 million in 1971.^[2]

Commissioning

Commissioning took place on 14 March 1972. In the summer 1972 timetable, 48 local services ran every working day on the line. Due to high track utilisation between Schwanheim junction and Frankfurt Hauptbahnhof, no regular-interval could be offered initially; there were irregular gaps of up to 60 minutes. According to traffic forecasts, an increase in services would be needed from 1978 at the latest. A regular-interval service of six S-Bahn services per hour and direction was considered necessary.^[4] 12,500 passengers per day were counted in August 1972, rising to 15,500 in the summer of 1975.^[4] At the beginning of operations there was no connection towards Kelsterbach/Mainz. All trains from the airport ended at the Hauptbahnhof, as the extension into the city centre had been cancelled.^[8]

Second construction stage

In a second stage, between 1976 and 1979, separate tracks were built for S-Bahn operations between Kleyerstraße junction and Schwanheim, with a new bridge over the Main.^[4] The 6.97 kilometre-long section of new S-Bahn line separates from the S-Bahn main line at Kleyerstraße junction about two kilometres west of the concourse at the Hauptbahnhof.^[4] It then crosses two ramps over the railway from Frankfurt-Höchst with grades of up to 3.6%.^[9] It then passes over the New Niederrad Bridge and through Frankfurt-Niederrad station^[9] until shortly before Stadion station it connects with the line opened in 1972 to the west of the existing tracks. A 210-metre-long platform was built in Sportfeld station as part of the work.^[4]

The construction was completed three months earlier than planned at the start of work. Scheduled operations commenced at the change to the winter timetable on 30 September 1979. Since no extensive timetable changes were required for operational reasons for the winter timetable, the operation of a full service commenced on 1 June 1980. It provided a ten-minute cycle with two S-Bahn lines (S14: Frankfurt–Mainz–Wiesbaden and S15: Hauptwache–Airport), amounting to 93 S-Bahn trains per day and direction.^[4] The travel time between the airport and the Hauptbahnhof was reduced by the new infrastructure from 18 to 20 minutes to 11 minutes.^[10]

In October 1975, the fundamental agreement for the "Development of the Airport S-Bahn including a second Niederrad Bridge" (Ausbau der Flughafen-S-Bahn einschließlich einer zweiten Niederräder Brücke) was made on the basis of the Municipal Transport Financing Act (Gemeindeverkehrsfinanzierungsgesetz) of 1972. Accordingly, the federal government financed 60 percent of the eligible costs of the local transport project and the rest was financed by the state of Hesse. Deutsche Bundesbahn financed the costs for additional S-Bahn multiple unit trains (class 420) and the costs for planning and construction supervision.^[4]

At the end of 1979, 20,000 passengers per day were counted on the line.^[4] The track infrastructure between Stadion and Kelsterbach were renewed during a three-week track closure in July 2007.