When I asked the question; 'drive north on which side of the Rhein to Cologne' the feedback response was overwhelming. Thank you to all the good people who have shared their experiences. Your help has been invaluable.
Now a follow-up.
Route 9 on the 'left' (west side of the river) appears to have less maintenance problems than the 'right' bank (east side), is it, route 42? My map software shows a bunch of red slash road signs that seem to infer road maintenance on the east side?
So my question; does one side of the river have a better road, in better repair, than the other??
Thanks again to you all. For me, a first time Blogger, you (and Rick) are the best.
There are roadworks now and then and I don't think they are more common on one side or the other. But, there was a landslide a while ago on the right side so the B42 is closed until the area can be secured.
The landslide was caught on camera: https://www.youtube.com/watch?v=VZmebZth2_s
There are a few images here: https://www.bild.de/regional/frankfurt/frankfurt-aktuell/lebensgefahr-bei-der-loreley-felsrutsch-legt-gueterverkehr-lahm-75745674.bild.html
Since your trip comes later in the year and since the damage was on the right side, it's my guess that the right side might be better than the left. But that doesn't mean the left will be in poor shape. Germany tends to be intolerant of damaged roadways; damaged spots tend to vanish quickly, and visiting drivers like you generally don't need to base their routings on such things unless the damage has just recently taken place. Check again just before you go.
Holy shnikeys Badger! That video was dramatic. Saw a follow up article from a few days ago that DB hopes to reopen the rail line by end April. Hopefully that means the highway will open then too.