I think this edit is incorrect - Esri World Imagery (Clarity) Beta shows that there is (or at least was) a traffic island here. The carriageway on either side of the island should therefore be mapped as separate ways, and this is how it was previously mapped. I therefore think this changeset should be reverted, unless the traffic island no longer exists.

Also, I suspect there is a missing turn restriction in the mapping here - do you know (from a source we are permitted to use here, so e.g. Google StreetView is not permitted) whether there are signs indicating that a U-turn from the A1 northbound to southbound is banned? The geometry I see in the imagery suggests that is likely to be the case.

(There is on exception I'm aware of to the general rule of using separate ways around a traffic island, which is for a small traffic island away from any junctions and which can be represented instead by a labelled node. However, that approach isn't possible here.)

In this changeset you've managed to move the way previously representing the farm access track to the removed highway alignment, and created a new way for the farm access track (I'd guess this happened by extending the way and then splitting it, with the history being assigned to the wrong half). Please try to avoid doing this, as it makes the history more confusing and misleading.

I've done something slightly different - changeset/76563347 fixes assorted issues, some of which were introduced here, and some of which were already present. Have a look at it and see if you agree and/or think I've missed anything.

I think you have misunderstood the meaning of many of the construction tags you have removed. They are being used to indicate what tags will be appropriate when all the construction at the junction is complete and the new roads are fully opened. Your edit removes all of these indications. I would agree that a few of the existing tags were incorrect, but a blanket removal of constuction: tags on all the roads that are open in some form (not necessarily their final form) seems incorrect.

I've reverted this in changeset/76562296; if it turns out that the roundabouts are fully open (which would surprise me), then this can be reinstated as a new changeset using appropriate refs for the temporary layout.

That GPS trace drawn in the image corresponds to the layout as it was mapped before your changes, and hence provides no evidence at all to support your changeset. If that is the only 'evidence', then this changeset should be reverted.

Do you have a source for this? I haven't yet seen any evidence that the roundabouts are fully open (though I am unable to check in person), and wasn't expecting that to happen while all A14 traffic was still passing through them.
Also, I don't think it's correct to label bits of this junction as the A141 yet - I wouldn't consider any of this as the A141 until the A14 is diverted onto the new bypass.

I don't see any reason for including the tag "oneway=no" - it's the default for this type of road, and there's no reason why any other mapper might think it weren't twoway.

I think the wiki page, along with existing usage, makes it fairly clear that "motorway_junction" is appropriate here.

You made various errors in this changeset, which I think I fixed in 76255908. Firstly, you used "trunk" instead of "trunk_link" in many places. Secondly there were a number of gaps where you left the old motorway status or refs. And thirdly, you changed the future status of a number of slip roads to incorrectly show them as forming part of the final layout.
You may like to check that all my changes are accurate and have fixed all the problems with your changeset.

The county council website suggests that the name changes at the corner of the parish boundary near Crome Lea Business Park. I've no idea if this is an admissible source anyway.
https://www.cambridgeshire.gov.uk/residents/travel-roads-and-parking/roads-and-pathways/highway-records/

Agreed - I've added highway:construction=primary_link to indicate again the status once construction is complete.

The way you had this mapped gives the impression that the busway is already open, which it isn't. I've added/amended tags to show that it is still under construction, but I don't know if any parts are actually (either in the way object I updated, or in the parts further north). Are you able to check how much of the busway is still under construction, and fix any other incorrect tags? If necessary, you may need to split some existing ways.

You shouldn't add descriptions such as 'planned' or 'construction' to names - this may 'clarify' to a human reader, but OpenStreetMap data is also used algorithmically (e.g. by journey planners). You should instead use construction tags (or other appropiate lifecycle tags) - read highway=construction and osm.wiki/Category:Lifecycle for more information.

I agree that you aren't the original source; however, all the ones I'd noticed where ones where you'd changed the tag barrier=fence to barrier=hedge, without noticing the issue.

I just discovered the tunnel issue (the level crossings being the giveaway) too - this could have been fixed a week ago when you first discovered the mistake. I've removed the incorrect tunnel/layer tags, but I don't have enough information to work out what needs to be done with the Yox River crossing, so you'll have to fix that yourself.

There are a number of areas east of Hardwick that you have tagged as barrier=hedge and landuse=farmland. There are a couple of issues with this. Firstly, the use of a 'landuse' tag suggests that this way should be treated as an area, with the result that users of the data might incorrectly assume the whole field is a hedge (see e.g. the default renderer on openstreetmap.org at zoom levels 16 and above). Secondly, by tagging this on multiple adjoining fields (setting aside the area issue), you are effectively mapping the same hedge multiple times.
I'm wondering if you might be able to resolve these tagging issues - my suggestion would be to remove barrier=hedge from the fields and tag the hedges on separate non-overlapping (and probably shorter) ways.
I realise this issue partly predates your changeset (where the fields were tagged as fences instead of hedges). However, as the last person to have mapped these fields, and since I've never visited them myself, you are probably better placed than me to work out how to tag sections of the hedge appropriately (including knowing whether there should be any gaps in the hedges).

Since you've adjusted the roundabout exit, you should probably adjust the entrance under construction to a more accurate line as well (compare this to the nearby Girton West roundabout)

Yes, I'm aware of that announcement (though I saw it on Facebook instead). However, plans do sometimes change, and the reality on the ground is clearly different. In a comment on their post they confirmed to me that:
"the information originally shared was our intended outcome. However, we then decided to keep the slip road open due to safety reasons. All traffic heading out on A1307 Huntingdon Road is being signposted to join the A14 at the new slip road."
"Safety reasons" apparently means avoiding a risk of people trying to get to the A14 and going the wrong way down the exit slip.

This is the second time you've set the slip road as oneway - before repeating a change that someone else (me) reverted, you should check what their sources are and whether the reversion was correct. In this case my edits to 'reopen' the slip road and make the link twoway clearly state that the source was a 'survey' - that means I was actually physically present and saw that the slip road hadn't been closed. Furthermore, I happened to be there again at the exact time you made this change to mark the slip road as closed again, and I can confirm that it was definitely still open at the time. I've reverted this changeset; if you still think that the slip road is permanently closed, then please discuss this further with me.