Bundesautobahn 42 is an autobahn in western Germany. It connects Kamp-Lintfort with Castrop-Rauxel, linking several large cities in the Ruhr area, such as Dortmund, Duisburg, the North of Essen and Gelsenkirchen. It is colloquially known as Emscherschnellweg, after the river Emscher, which it roughly follows. Wikipedia