Tom Tom updates map automatically?

was 175ps Mazda CX-5 Auto AWD Sport Nav, now 190ps DSG Tiguan 4M
I updated my map some months back using the once only free update, not been on tt home since.

Now I travel on the A57 near Todwick regular , those that know that stretch of road cant help but notice the road works where a dual carriage way is being built to replace the original road.

When part of the new road was opened as expected the map showed the car travelling through a field, then over a period of time I noticed a tether for want of a better word that attached to the original road onto the car image. And gradually the car was no longer travelling through a field, but on a road but with red dashes or similar.

Now weeks later my map shows the new road ! How does it do it?

As I've said I've done no map updates, so how does TT achieve this "map building", I find it the only thing about TT that impresses.
I can only speculate on this one but based upon many years experience of TT products I can't think of anything else.

I suspect that your car is " learning" that the road location has changed and updating the map itself. Then, if and when you next connect to TT home (guess you will have to do that for the software update just launched :). ) it will transmit the changes back to TT via the Mapshare function such that they will be included in a future map release. The only way one could prove/disprove this theory would be to have another car with the TT sat Nav drive along the same stretch of road to see if their map had changed also, I suspect not. If the maps were to be auto-updating this would deprive TT of the revenue stream generated by new map update subscriptions. Normally the Mapshare corrections downloaded each time you connect to TT only influence things such as restricted turns e.g. No left/right turn where the map says you can or one way streets. It certainly doesn't download new roads.

I don't now bother with new map updates. Some years back a roundabout was removed in Swindon and replaced by a major crossroads with numerous sets of traffic lights, new filter lanes etc. A year later and despite four quarterly updates this still wasn't reflected on the "new" maps......

As an aside, it's good practice to update your SD card via TT on a regular basis for two reasons, firstly that it will upload the latest speed camera database included in the Live services and also because I believe it also downloads something known as QuickGPS Fix which basically updates the expected position in the sky of the satellites used for GPS positioning. As the name suggests this should allow your Nav unit to fix its position on start up more quickly each time.
I was told at the dealer that it needs to be updated, so I pulled the card and d/l the update, it was really easy.