The plan is to build a replica of the Rheinuferbahn between Bonn and Cologne. The route is particularly suitable because of the intercity route, which would be something new in TSW with a light rail system. The route should be accessible with the K5000 light rail car on line 16. Section to be built: Köln-Rodenkirchen - Wesseling - Bonn Hbf (extension possible)
Interesting, I live in Cologne so I’m curious to see what you come with, I was also planning on making Linie 12 with a bit of 15 in the middle, even had the KML and SRTM ready, but decided to make Köln - Düsseldorf instead. Good Luck