Introducing the...
𝙍𝙝𝙚𝙞𝙣-𝙍𝙪𝙝𝙧 𝙋𝙪𝙗𝙡𝙞𝙘 𝙏𝙧𝙖𝙣𝙨. 𝘾𝙝𝙖𝙡𝙡𝙚𝙣𝙜𝙚
A challenge to use only local ÖPNV (aka. Public trans.) to traverse the Rhein-Ruhr metropolitan region!
Rules:
1. You must travel between Dortmund and Köln, either direction is fine. Any reasonable routing is allowed. Extension beyond Köln and Dortmund is allowed
2. You may use the following modes: 
buses, 
trams, 
Stadtbahnen, 
trolleybuses, or 
Schwebebahn
3. Prohibited modes during the challenge : 
Bahn, 
Regional trans., Fernverkehr, u.a.
4. Logpflicht: You must log your challenge, z.B. on Fedi, Träwelling, or Travelynx