What sort of fixes are these - your comment isn't particularly descriptive. Since this is a bunch of independent fixes (as opposed to representing a simultaneous widescale change in the real world), then it might have been clearer to break them down into separate sets of related changes, with helpful comments. It also makes it easier to revert any errors you make.

Looking at the changes, I think there are a few errors here, or places where you've made changes away from a convention I would use:

1. You marked the roundabouts at New Ellington junction as fully open. I've seen various comments from people reporting that they are still not fully open, and I have already reverted their opening once in the past 36 hours. If you'd looked at recent changeset history in the area (e.g. osm.org/history#map=12/52.2842/-0.0233) then you'd have seen that I had a well-sourced changeset marking it as closed again. Given the volume of changes currently happening in the area, I think it is wise to check the changeset history so as not to unnecessarily cause 'edit wars'.

2. You've removed the ref and name from a number of roundabouts. This contrasts with how I would currently tag roundabouts, and what appears to be the local practice, although I am aware that at least one wiki page currently supports your approach.

3. What is your basis for changing the minor road from Brampton across the A14 towards Grafham from 'tertiary' to 'unclassified'?

Does this changeset mean that the Krispy Kreme previously mapped here has closed. You should try to include a changeset comment that makes it clear what the changeset does (e.g. "Krispy Kreme no longer exist in the Grafton Centre"), along with a source tag to indicate how you know this this (e.g. "from a friend who visited last Friday")

You also missed out the A14 EB exit slip at Swavesey - I've added this in changeset/78121338.

A few errors I've corrected, and a query.

First the query: Do you have a source for showing the operator of the A1307 under Spittals interchange as Cambridgeshire County Council? I would have expected the limit of responsibility to be further towards the centre of Huntingdon, but I haven't checked this yet.

The corrections:
You got the junction number for Girton wrong - it's been confirmed by A14C2H on Facebook that Girton interchange will remain J31, and they're still referring to the (temporarily) remaining Dry Drayton slip as J30. Fixed in 78120528.

I'm pretty sure the A1307 on Views Common will be a dual carriageway all the way to the roundabout - that is what is shown in official documents from August, the map from last year, and the prior mapping on OpenStreetMap (although admittedly I hadn't noticed that the under construction roundabout hadn't been linked to the A14 carriageways). You must surely have had some reason for changing this, but in the absence of any evidence to support it so far, I reverted that part of the change in 78120833. If you still disagree, then it should be easier to discuss or re-revert changes on the smaller changeset.

You forgot to list Brampton Hut and Spittals as part of the A141 (fixed in 78120933)

For some reason you merged non-embankment ways and embankment ways between Brampton and the Ouse. This might actually be correct, but doing so as part of a changeset to reflect this weeks opening is confusing and makes it harder to check your sources and verify it wasn't an error. I reverted this change in 78121088 (believing it to be a mistake at the time), but if it's was intended, then you should revert my revert and include a helpful changeset comment and source.

There's also a stray reference to the A14 on the motorway section of the Alconbury spur - I haven't fixed that yet, but will probably do so soon once I've worked out a sensible way to map it.

It looks like your editor has included some London bus route relations in your changeset, despite these relations being unchanged in this changeset. This is probably a bug with JOSM, so I suggest you see if you can find any information (e.g. previous bug reports) on the internet, and raise a report if needed.

I presume the actions you took involved implementing and uploading changeset/78005364, which modified these bus route relations as a consequence of splitting a way to add a turn restriction. You then continued using JOSM without restarting it, triggering a bug in the process.

I am aware that many people have reported bugs in JOSM involving creating multiple changesets in a single session, so I think this is somthing to try and avoid. In particular, if you're subsequent changeset is in a completely different geographic location, then there's virtually no cost to restarting JOSM as you have to download a completely new set of data anyway.

Another thing you can do to help avoid errors in changesets (either your own errors or those introduced by bugs) is to have a look at the list of changed objects in the uploaded changeset. This might not catch everything (and in this case it's possible the bug wouldn't have been visible at that stage), but it should catch some mistakes (I know it's caught some for me). If you do spot a discrepancy, then the 'upload in selection' open might be helpful - or it may be better to restart JOSM and create the second changeset separately.

I think you've reverted the layout to an older set of plans - the layout you've mapped here is the one shown in the Section 6 map dated May 2018, but the Huntingdon Town Centre leaflet dated August 2019 shows the layout that was in OpenStreetMap prior to this changeset. If you'd looked at the way history (which is generally a good idea if you're modifiying existing mapping) you'd have discovered that the layout you've drawn was present in OpenStreetMap until 10 days ago, when Thingummy modified it in https://overpass-api.de/achavi/?changeset=77983647
Since the more recent document shows Thingummy's layout, I suggest that you revert to that layout.
(Incidentally, there is evidence elsewhere that the scheme maps on the website don't show the latest plans - for example, the Cambridge Crematorium access road was built in a different location to the one shown on the plans).

There was some discussion of the A14 bypass opening here, in which it was recommended that it isn't marked as open in OpenStreetMap until Monday morning. This recommendation was seemingly ignored. I suggest reverting changesets 77903602, 77902225 and 77902052 to get back to map data that is more accurate for the present, and to fix various other minor issues introduced in those changesets.

highway=motorway_junction was correct - this tag is used even where the road in question isn't actually a motorway.
See highway=motorway_junction

Also, when splitting a way, try to preserve the history on the most substantial/significant portion of the way. In this case you kept the history on the tiny stub you created near Swavesey. (I disagree with splitting that way as well, but that's probably better discussed on your earlier changeset.)

I think this changeset is rather misleading and confusing - the road isn't open yet, you've deleted some of the under-construction bits leaving a strange gap, and made it difficult to work out what's happening near the Swavesey junction. I think it should still be mapped as under construction until Sunday length - there's certainly no reason I can see to partly 'open' it now.

The most obvious issue is the bit by Cambridge North station which is used by the Citi 2 buses as well as the busway buses. Beyond that it comes down to a question of whether the tag "bus_guideway" is appropriate for routes that are restricted to guided buses but physically guided. I disagreed with Borbus about this on changeset/71344354; I'd be interested to hear your opinion too.

Is the ford really at 0.1m below sea level? It seems unlikely, so it looks like you might have misinterpreted the tag.

This changeset accidentally displaced 18 nodes by a few metres. I reverted that accidental change in 77174289

I think this is also an issue in changesets 76617069 and 76685993; I haven't checked to see if you've made similar edits in any other changesets.

I've just noticed this changeset, and I disagree with the tagging. You may be correct that these aren't ' normal highways', but they aren't bus guideways either - highway=bus_guideway should be reserved for sections that are physically guided (including perhaps brief road crossings where the guidance resumes immediately after the crossing). The wiki suggests (and I agree) that highway=service would be more appropriate, perhaps in combination with access=no and bus=designated (or something else consistent with local usage).

highway=bus_guideway

I've just noticed this changeset, and it looks like you've changed a lot of ways to highway=bus_guideway where these sections are not guided (and in some cases are used by unguided buses as well). I think this is incorrect tagging - highway=bus_guideway should be reserved for sections that are physically guided (including perhaps brief road crossings where the guidance resumes immediately after the crossing). The wiki suggests (and I agree) that highway=service would be more appropriate, perhaps in combination with access=no and bu=designated (or something else consistent with local usage).

highway=bus_guideway

Oops, I forgot that one - thanks!

This change is wrong - the old A14 exit slip is not a motorway (let along a motorway_link), never has been, and never will be. Access=no is unnecessary because it is no longer tagged as an extant highway (it might still physically exist for a few days, but leaving it tagged as a highway would be more confusing and difficult to keep up-to-date). I have reverted this change in changeset/76936447

Oops, I forgot to use _link on the turning lanes.
osm.wiki/Highway_link says "The _link tags are used to identify slip roads/ramps and "channelised" (physically separated by an obstruction or painted island) at-grade turning lanes" - in this instance there are physical islands forming part of a larger painted island, and knowing about these would be useful for someone trying to walk.cycle round here (as a cyclist trying to get towards Milton I miss my intended turning at this junction more often than not). There was also the anomaly of a pedestrian/cycle crossing where there was no highways drawn through it.
I'll change the turning lanes the turning lanes to links; let me know if that's better.

I've now reverted this changeset, and added the no U-turn restriction, in changeset/76881246

Hi Stu,

Firstly, here are a couple of initial links that you might find relevant:
osm.wiki/Highway_link
osm.wiki/Junctions

In general, I reckon there are two good ways of finding out how to map things - either look for similar situations elsewhere on the map to see how they are mapped, or search on the internet to see what other people have written about mapping that sort of feature. In particular, browsing the wiki is probably a good way of finding some of the latter information. However, you should bear in mind that there is often more than one to map things (e.g. sometimes there's an accuracy/time trade-off), and there's sometimes disagreement between different contributors. Many proposals that are made never become widely accepted.

As for your last paragraph: Usually the the angle at which ways are drawn is some compromise between representing the point at which two ways join, and representing the centrelines near the join in a consistent way. So a single carriageway becoming a dual carriageway cannot avoid including a wiggle in the line mapped for traffic in each direction, but in the case of a slip road this can often be avoid by extending the sliproad's way along its centre line to meet the mainline before actual diverge point. Routing often doesn't care about the exact geometry at the intersection - any constraints are represented by oneway roads or explicit turn restrictions. And I've no idea what you mean by "road type progression", but I think you can probably find some helpful information by searching the wiki or the wider internet.

As for this changeset/junction, I think the best way to proceed would be to revert this changeset (since the previous version probably had appropriate geometry) and add the turn restriction - if you're not sure how to do that then I can easily do it for you later.