From 1872, the Swiss National Railway (Schweizerische Nationalbahn; SNB) tried to establish competition with the existing railway companies with a second rail link between Lake Geneva and Lake Constance (Bodensee).
Originally, the National Railway planned a line from Aarau via Olten through the Gäu to Solothurn and on to Lyss.
Along with the NOB, the SCB made daring commitments to build new lines to fight the competition.
In 1872, the SCB entered into an undertaking with the canton of Solothurn to build the Gäu Railway (Gäubahn; Olten–Solothurn–Lyss, now considered part of the Jura Foot Railway), along with the Solothurn–Biberist branch line (now considered part of the Solothurn–Langnau railway).
In return, Solothurn demanded the creation of the Waterfalls Railway (Wasserfallenbahn) from Liestal through the Jura to Solothurn and its continuation from Solothurn to Schönbühl near Bern.
The SCB also committed to build a local railway (Lokalbahn) from Liestal to Waldenburg and to participate in the  Sissach–Gelterkinden tramway (Sissach-Gelterkinden-Bahn), including funding a third of its construction costs.
The SCB increased its share capital from CHF 37.5 to 50 million in 1873 to finance the construction of new lines and the duplication of parts of the old network.

When Alsace-Lorraine was ceded to Germany as a result of the Franco-Prussian War in 1871, attempts were made to build a rail link from Delle to Lucerne via Delémont and Langenthal (Jura–Gotthard Railway).
In addition, the Bern-Lucerne Railway (Bern-Luzern-Bahn; BLB) planned a line to the Gotthard via Langnau.
To defend against this double competition, the SCB began construction of the Langenthal–Wauwil railway.
It would have connected the Olten–Bern and the Olten–Lucerne lines and significantly shortened the detour via Aarburg.

However, the raising of additional funds was difficult due to the economic crisis and led to significant restrictions on the construction program.
The construction of the Waterfalls Railway and the Langenthal–Wauwil line, in which CHF 3.5 million had already been invested, had to be abandoned.
The payment of dividends was discontinued and the net income of 2 ½ years was used to write off the construction costs of the discontinued lines.
In 1881, the unrealised Waterfalls Railway cost the SCB the deposit of CHF 125 000 that it had paid for the concession.
The construction of the Waldenburg Railway was left to a special undertaking.

The SCB had more success with the joint ventures with the NOB.
The SCB together with the NOB built the Bözberg Railway from Pratteln to Brugg AG from 1871 to 1875 and the Aargau Southern Railway (Aargauische Südbahn), which connected their lines to the Gotthard Railway from Rupperswil via Wohlen to Immensee, operated by the Central Railway, from 1873 to 1882.
The opening of these two lines led to a decline in traffic on the Hauenstein line.

The construction of the Basel Connecting Line also occurred in this period.
In the Treaty on the Construction and Operation of the Gotthard Railway, Switzerland undertook to connect its network with the Baden Railways by rail over the Rhine.
The Basel Connecting Line was built by the SCB together with the Grand Duchy of Baden State Railways and put into operation on 3 November 1873.
A year before, the section of the Strasbourg–Basel railway from the French border at St. Ludwig to the Centralbahnhof was transferred from the Chemins de fer de l'Est to the SCB under a federal decree.
The Salinenbahn (Salt Railway) from Pratteln to the Schweizer Salinen (Swiss salt works) at Schweizerhalle was opened on 28 October 1872.
From 1872, the Swiss National Railway (Schweizerische Nationalbahn; SNB) tried to establish competition with the existing railway companies with a second rail link between Lake Geneva and Lake Constance (Bodensee). Originally, the National Railway planned a line from Aarau via Olten through the Gäu to Solothurn and on to Lyss. Along with the NOB, the SCB made daring commitments to build new lines to fight the competition. In 1872, the SCB entered into an undertaking with the canton of Solothurn to build the Gäu Railway (Gäubahn; Olten–Solothurn–Lyss, now considered part of the Jura Foot Railway), along with the Solothurn–Biberist branch line (now considered part of the Solothurn–Langnau railway). In return, Solothurn demanded the creation of the Waterfalls Railway (Wasserfallenbahn) from Liestal through the Jura to Solothurn and its continuation from Solothurn to Schönbühl near Bern. The SCB also committed to build a local railway (Lokalbahn) from Liestal to Waldenburg and to participate in the  Sissach–Gelterkinden tramway (Sissach-Gelterkinden-Bahn), including funding a third of its construction costs. The SCB increased its share capital from CHF 37.5 to 50 million in 1873 to finance the construction of new lines and the duplication of parts of the old network.
When Alsace-Lorraine was ceded to Germany as a result of the Franco-Prussian War in 1871, attempts were made to build a rail link from Delle to Lucerne via Delémont and Langenthal (Jura–Gotthard Railway). In addition, the Bern-Lucerne Railway (Bern-Luzern-Bahn; BLB) planned a line to the Gotthard via Langnau. To defend against this double competition, the SCB began construction of the Langenthal–Wauwil railway. It would have connected the Olten–Bern and the Olten–Lucerne lines and significantly shortened the detour via Aarburg.
However, the raising of additional funds was difficult due to the economic crisis and led to significant restrictions on the construction program. The construction of the Waterfalls Railway and the Langenthal–Wauwil line, in which CHF 3.5 million had already been invested, had to be abandoned. The payment of dividends was discontinued and the net income of 2 ½ years was used to write off the construction costs of the discontinued lines. In 1881, the unrealised Waterfalls Railway cost the SCB the deposit of CHF 125 000 that it had paid for the concession. The construction of the Waldenburg Railway was left to a special undertaking.
The SCB had more success with the joint ventures with the NOB. The SCB together with the NOB built the Bözberg Railway from Pratteln to Brugg AG from 1871 to 1875 and the Aargau Southern Railway (Aargauische Südbahn), which connected their lines to the Gotthard Railway from Rupperswil via Wohlen to Immensee, operated by the Central Railway, from 1873 to 1882. The opening of these two lines led to a decline in traffic on the Hauenstein line. 
The construction of the Basel Connecting Line also occurred in this period. In the Treaty on the Construction and Operation of the Gotthard Railway, Switzerland undertook to connect its network with the Baden Railways by rail over the Rhine. The Basel Connecting Line was built by the SCB together with the Grand Duchy of Baden State Railways and put into operation on 3 November 1873. A year before, the section of the Strasbourg–Basel railway from the French border at St. Ludwig to the Centralbahnhof was transferred from the Chemins de fer de l'Est to the SCB under a federal decree. The Salinenbahn (Salt Railway) from Pratteln to the Schweizer Salinen (Swiss salt works) at Schweizerhalle was opened on 28 October 1872.
Swiss Central Railway