Thank you for your reply. Apologies if my intention to write a comment was not clear - I didn't mean to say I somehow know better and could confidently improve this changeset, nor did I mean to discredit your intention and effort in attempting to improve geometries, both for this changeset and other calibration works you have done - I simply wanted to point out a few things that I assume you overlooked while working on this. Sorry if that was not clear in my initial comment.

Regarding aerial imagery, I am aware that ESRI imagery is preferred. When I used the iD editor to inspect this area, only the ESRI imagery seems to supports the new geometries, while Bing, "ESRI Clarity Beta", and Mapbox all show a much straighter tunnel approach. This led me to think that the new geometries were due to ESRI's or the altitudes's distortion, hence points 1 and 2.

Regarding barriers for editing, I honestly did not have a clear "other tools" in mind when I said "I would suggest using other tools to verify the alignment". I just thought "mappers more experienced than me might have better ideas of which mapping techniques to use in a specific situation, so maybe they can try alternative tools here to clear things up!", which is why I wrote that point.

Regarding absolute accuracy and balancing, while I understand that it's impossible to have pixel-perfect alignment with the real world and that compromises have to be made, the problems I pointed out in point 4 are just too obvious imo; it goes beyond what I personally consider to be "reasonable" curves. It seems like the west-bound tube is bent south suddenly at the end of it, just so that it fits the aerial imagery without needing to modify the other parts of the tunnel? No insult intended, but it feels like a very lazy and minimal workaround to avoid dealing with the bigger question of the accuracy of the geometries of the tubes and the eastern portal. At the very least, the transition from the existing data that was not modified to the new data should be somewhat believable, unlike that current mapping, which is blatant enough that an unexperienced user like me noticed something's wrong just by taking a glance.

Now again, I'm not saying that I can do better or improve on this; I just want to point out things you probably didn't consider while working on this so that you can make a better judgement on what to do with this changeset.