As time progresses so does the type of road a city uses to pave its streets. When new buildings are built the current road type will be applied to all surrounding roads, upgrading any older city roads in the process. All new city roads are built using the current road type.
However if an older city road wears out it will still be renewed with the old road type rather than being renewed with the current city road type. This means well developed areas which have stagnant building growth might maintain old city roads far longer than makes sense, especially seeing how they are filled with premium/highly developed housing. They will eventually be upgraded, but only when new types of high development city buildings become available or the old city road type completely obsoletes so cannot be renewed.
As soon as cities start to use a new city road type, all city roads should have their renew type changed to this new city road type. If the deployment of the road type is too quick then maybe some staggering on a city by city basis could be used to represent slow adaptation of a new city road standard.
It appears inter-city roads do correctly upgrade replacement type, just not city roads.
Thank you for letting me know. I have now modified the behaviour as suggested. I should be grateful if you could confirm whether this is working with to-morrow's nightly build and onwards.
Nightly build deployment seems to have failed today.
I am not entirely sure why that happened - I suspect that there must have been a scheduled restart for updates during the rebuild process. In any event, it is back up and running now.
Seems fixed. All old city roads are now scheduled for renewal with the current city road type.
However the costs are inconsistent, not that it matters as no one pays. Renewing cobblestone road into cobblestone road is quoted by the detail UI to be more expensive than upgrading dirt road into cobblestone road.
Splendid, thank you for confirming.