At January 1, 1877 the Bülach-Regensberg-Bahn got bought by the Swiss Northeastern Railway (NOB), which made the acquisition to fight a possible competition by the Swiss National Railway (SNB) by providing a shorter connection between Winterhtur and Baden.

The extension of the Wehntal railway till Niederweningen was already planned at the time of the purchase by NOB, but was only realized 1891.

A further extension of the railway line through the Surb valley was planned since the mid-19th century, but was never realized.

After World War II the Wehntal railway was threatened to be closed due to sparse traffic.

There the steam operation lasted only a few weeks longer than on the Wehntal railway line.