Upgrading works were begun near Plochingen at the upper end of the intended waterway and plans existed to make the Fils between Plochingen and Göppingen navigable. The area for a harbour in Göppingen remained reserved in spatial planning until 1978. The construction chairman Konz also ordered the planning of a tunnel through the Swabian Jura for a waterway Ulm at the Danube in order to create a waterway between upper Rhine and upper Danube, as the State treaty from 1921 had planned. But those plans were dropped from 1968 onwards.