Sieg Railway
The high-speed line's dedicated track begins in Cologne-Porz and are located between the Sieg Railway and the line from Gremberg yard and the Cologne south bridge, which, in effect, becomes the Right Rhine line when it separates at Troisdorf. Between Porz and Troisdorf there are six parallel lines and the speed limit on the HSL is . At Troisdorf the HSL runs through a tunnel under connecting lines that allow passenger trains running on the Sieg line to transfer to the Right Rhine line and freight trains on the freight lines to transfer to the Sieg line (and vice versa for northbound trains).