[7] The planners revised their initial considerations of St. Ingbert as the western terminus, under pressure from Prussia, which wanted to have the long-term connection to Saarbrücken passing as far as possible over its own territory.

Due to financial stringencies, Bavaria rejected direct intervention, but the Saarbrücken Committee agreed to take over the costs on condition that the line was linked to the Saarbrücken–Sarreguemines railway.

[17] After the end of the war, the construction of a main railway from Bruchsal via Germersheim, Landau and Zweibrücken to St. Ingbert was planned, which was finally built in the period from 1872 to 1877.

Its main purpose was to provide a connection for coal trains from the Saarbrücken area to the South Palatinate Railway (Südpfalzstrecke; Landau–Zweibrücken), which opened in 1875, to avoid the detour via Neunkirchen and Bexbach and a reversal in Homburg station.

[24] A connecting curve in the Saarbrücken district of Halberg from the Scheidt direction towards Brebach on the line to Saargemünd (the official name of Sarreguemines at the time) was commissioned on 29 July 1905.

[31] The Homburg–Saarbrücken section became part of the newly created Territory of the Saar Basin (Saarbeckengebiet) on 10 March 1920, which was founded at the initiative of the victorious powers under the Treaty of Versailles with a duration of 15 years under League of Nations control.

[38][39] After the outbreak of World War II on 1 September 1939, the line was again used by numerous military transports; as early as 1938 deportations to Dachau had taken place in Kaiserslautern and Ludwigshafen.

[42] After the Western Front reached the Palatinate in March 1945, the US Army resumed operations on the section of the line to the west of the Rhine to procure supplies.

[47] The section of the line to the west of the Rhine came to under the control of the Vereinigung der Südwestdeutschen Eisenbahnen (Union of south-west German railways) from 1947 to 1949 during the French occupation.

The Germersheim Rhine Bridge, which was rebuilt in March 1945, contributed to the fact that through traffic increasingly concentrated on the main line from Mannheim to Saarbrücken.

[54] The development program for the network of Deutsche Bundesbahn presented in 1970 contained a newly built railway (Neubaustrecke) between Hochspeyer and Ludwigshafen on a straightened route by 1985.

The only option involving an upgrade of the existing line, estimated to cost 415 million Deutsche Marks, would have enabled a travel time reduction of 21 minutes.

A third option with a new line between Saarbrücken and Hochspeyer largely parallel to Bundesautobahn 6 with an estimated cost of 1.8 billion D-Marks would have provided a travel time reduction of 18 minutes.

In the middle of 1993, an expert report was commissioned by the State of Rhineland-Palatinate and the Federal Ministry of Transport, which presented four different options for new and upgraded lines on the Hochspeyer–Neustadt section.

In May of the same year, the Federal Government and Deutsche Bahn signed a financing agreement worth 351.4 million DM to upgrade the line between Mannheim and Saarbrücken.

The introduction of the S-Bahn operation resulted in the modernisation of the stations along the line; The platforms have since been raised to a height of 76 centimetres to enable level access to the trains.

The route through the Palatinate Forest with its numerous tunnels between Neustadt an der Weinstraße and Kaiserslautern remained structurally unchanged contrary to the original plans.

With the introduction of the Saar-Palatinate regular interval timetable (Saar-Pfalz-Takt) there were hourly operations between Mannheim and Saarbrücken with Intercity (IC), D-Züg and Eilzug services.

Trains carrying combined transport within the European Union are dominated by containers, swap bodies, semi-trailers and other goods at high freight rates.

Other marshalling yards, which were the starting point for Nahgüterzug ("local goods train") traffic, were located in Saarbrücken, Homburg, Neustadt and Ludwigshafen.

There are large freight yards in Neustadt an der Weinstrasse, Kaiserslautern (mainly for the Opel plant), Homburg (Saar) and at the terminus in Saarbrücken.

At the Hauptbahnhof it runs past Mannheim Palace, where it branches off from the western approach to the Riedbahn, then rounds a sharp curve to the Rhine and thus the state border between Baden-Württemberg and Rhineland-Palatinate.

On the 33.5 kilometre-long section between Neustadt an der Weinstraße and Kaiserslautern, the line climbs through a height difference of 109 metres and passes through a total of twelve tunnels.

West of Lambrecht, the line follows the valley of the Hochspeyerbach through several gorges, the meanders of which have been shortened by several tunnels: Lichtensteiner-Kopf, Retschbach, Schönberg-Langeck, Mainzer Berg, Gipp, Köpfle, Eisenkehl and Kehre.

In Rohrbach, it meets the line from Landau, which comes from the southeast; shortly earlier the railway crosses the autobahn, which then continues parallel to the south.

The section to Scheidt (Saar) runs almost level, but from the eastern end of St. Ingbert station it rises more steeply with a maximum climb of 1.05% until it reaches its first crest of about 272 m a.s.l.

The long-distance railway on the Schifferstädter bypass climbs at a maximum gradient on the newly built section of 0.8% and then falls at first at over 0.7% and then runs almost level parallel with the S-Bahn (Schifferstadt lies at 103 m a.s.l.).

The maximum permissible speed shortly after Limbach is 150 km/h, but, due to a narrow curve radius before Homburg (Saar) Hauptbahnhof, it is reduced to 110 km/h (120 km/h in the opposite direction).

[152] The interests of Paul Camille Denis, the builder of the Ludwig Railway, played an important role in the origin of the earlier Frankenstein (Pfalz) station.

[165] From the 1920s onwards, the company of Formsandwerke Ludwigshafen am Rhein, which quarried moulding sand and transported it by cableway to the station, was a significant freight customer.