Erlinsbach, Solothurn

Erlinsbach is a municipality in the district of Aarau of the canton of Aargau in Switzerland.

Gösgen District is one of the ten districts of the canton of Solothurn, Switzerland, situated to the northeast of the canton. Together with the Olten District, Gösgen forms the electoral district of Olten-Gösgen. It has a population of 24,793 (as of 31 December 2020).

The Eppenberg Tunnel is a railway tunnel in the Canton of Solothurn, Switzerland. It is part of the 'Future Development of Railway Infrastructure' plan (German: Zukünftige Entwicklung der Bahninfrastruktur or 'ZEB') and increases capacity on the Aarau–Olten line in the Schönenwerd–Däniken section. A particularly constraining bottleneck in the Swiss rail infrastructure is in the section between Aarau and Olten, which has only two tracks at Eppenberg-Wöschnau, Schönenwerd and Gretzenbach. The route has to be shared by international and national passenger trains as well as freight. Hence quadrupling the complete line between Aarau and Olten has high priority among infrastructure projects. The main purpose of the tunnel is to increase capacity. The two additional tracks in parallel with the existing double track line will effectively create a four track line. The Council of States adopted the law authoring the 'ZEB' programme in the spring session of 2009, authorising the budget for the Eppenberg tunnel. Due to the large financial requirements for the New Railway Link through the Alps project, construction of the Eppenberg tunnel only began in 2015.

Salhöhe Pass (el. 779 m.) is a mountain pass in the Jura Mountains of Switzerland between Kienberg in the canton of Solothurn and Erlinsbach in the canton of Aargau. It connects Kienberg in Solothurn and Erlinsbach in Aargau. The pass road has a maximum grade of 9 percent. Although it is the shortest route between Aarau and Basel, traffic over the pass is moderate. After the Bern citizens had conquered the Unteraargau region in 1415, Salhöhe marked the border between the Old Swiss Confederacy and the Further Austrian possessions of the Habsburg dynasty.

Gretzenbach is a municipality in the district of Olten in the canton of Solothurn in Switzerland.

Schönenwerd is a municipality in the district of Olten in the canton of Solothurn in Switzerland.

Niedergösgen is a municipality in the district of Gösgen in the canton of Solothurn in Switzerland.

Stüsslingen is a municipality in the district of Gösgen in the canton of Solothurn in Switzerland. On 1 January 2021 the former municipality of Rohr merged into Stüsslingen.

Schönenwerd railway station (German: Bahnhof Schönenwerd) is a railway station in the municipality of Schönenwerd, in the Swiss canton of Solothurn. It is an intermediate stop on the Olten–Aarau line and is served by local trains only.

Aarau District is a district in the Swiss Canton of Aargau with administrative capital Aarau encompasses the agglomeration of Aarau south of the Juras.

Eppenberg-Wöschnau is a municipality in the district of Olten in the canton of Solothurn in Switzerland.

The Wasserflue is a mountain of the Jura, located north of Erlinsbach in the canton of Aargau. It lies on the range east of the Salhöhe Pass. An antenna is located on the summit