Koln Deutz - Hamm is 148.1km via Dortmund
Mind you, there are three potential routes for Köln to Hamm. As to Bruxelles-Midi, via the classic or HSL?
You can go from Cologne to Dortmund via Düsseldorf-Duisburg-Essen-Bochum, Düsseldorf-Duisburg-Oberhausen-Herne, Düsseldorf-Duisburg-Essen-Herne or Solingen-Wuppertal-Hagen, which did you choose?