The Tuttlingen–Hattingen railway line, also called the Hattingen curve, is a railway line Baden-Württemberg, Germany. It runs 8.5 kilometres (5.3 mi) from Tuttlingen to Hattingen (Baden), creating a north–south line that bypasses Immendingen to the west. The line forms part of the Gäubahn between Stuttgart and Singen (Hohentwiel).