Schloss-Röttgen-Tunnel

In early 1992, the plans for this section did not yet include a tunnel. By late 1995, a 400-metre structure was envisaged. During the planning approval procedure, for which the documents were submitted in 1996, an extension was added. In mid-1999 and early 2000, the planned length stood at 517 metres each time.

The operators of the Röttgen stud farm sued to stop the project. Their concern was that the noise of trains on the planned airport loop could harm breeding success. In spring 1999, the Higher Administrative Court of Münster provisionally rejected a demanded construction freeze after a summary review, because the lawsuit was unlikely to succeed. After more than a year of dispute, the court followed an expert opinion by the lawyer and dressage rider Reiner Klimke. He took the view that horses quickly get used to the sound of passing trains. The feared tunnel boom never occurred.

In the end, the state of North Rhine-Westphalia and the Mehl-Mühlen-Stiftung agreed on a compromise: the tunnel was extended by 530 metres to 1,047 metres. Once the plans had been amended accordingly, the foundation withdrew the last of its three lawsuits before the Higher Administrative Court. As a result, the planning approval took effect on 2 February 2001. The direct additional costs amount to 7.7 million euros.

Preparatory work began in February 2000, with open-cut construction initially planned. Privacy fences were meant to shield the breeding operation from disturbance. To reduce the impact of the construction site, the tunnel was built in sections. According to Deutsche Bahn, the negotiations with the stud farm delayed construction by around 18 months, so the loop was not ready when the high-speed line opened in 2002. Since opening together with the airport loop, long-distance, regional and S-Bahn trains have run through the tunnel.