Hello Howard,
found some tunnel portal pictures for you: KBS 474 / KBS 248 3005 (KBS 478, 12478 / KBS 248m) 3002 (Stillgelegt, Radweg / KBS 248h) 3015 (Radweg / KBS 248q)
"Radweg" => cycling path, in this context it means that the line in question has been built back.
"Stillgelegt" => disused, out of service
Pictures are mostly from this millennium so beware on the ballasting seen in the pictures ... and thus not much smoke stains either since the steamies weren't running there anymore since the late 1960ies/ early 1970ies ...
Best Regards,
Christian
Edit: KBS = "Kursbuchstrecke" and some (mostly branch) lines' KBS numbers have changed with time twice or thrice
Edit #2: the lines listed are all left of the Rhine river and north of the Moselle river, i.e. the Eifel mountains.