	In September 1862, the Royal Württemberg State Railways () planned to build a railway from Illingen via Vaihingen an der Enz and Weil der Stadt to Calw. It did not pursue this project for long because the Kingdom of Württemberg had begun negotiations with the Grand Duchy of Baden in order to build the Nagold Valley Railway from Pforzheim. In February 1865, the Baden Government agreed to the construction of this line.