A year later the project was granted by the authorities of the canton Aargau, but was not executed, mainly due to disagreements over the exact line through the narrow valley.

Eventually the section between Beinwil am See and Menziken was built and opened in 1883 by the Seetal Railway (now SBB).

The opening of the Wynentalbahn (WTB) between Aarau and Reinach was on March 5, 1904, the extension to Menziken followed a few weeks later on 1 May.

Originally the line had its starting point in the street on the north side of SBB's Aarau railway station.

Here, however, from the beginning on, a narrow gauge electrically powered line was planned, in the largest part of the route to be operated as a tramway.

The project of the company Brown, Boveri & Cie (BBC) received the license and soon thereafter the construction works began.

[1] On 24 June 1958 the AS and WTB companies were merged to form the Wynental- und Suhrentalbahn (WSB).

[1] The new company faced two challenges; the fact that its two lines were not physically connected and the impact on services caused by increasing motor traffic interfering with its still largely street running tracks.