Hi Dian,

Under Victorian road rules, painted traffic islands are treated for the most part as physical barriers. Mapping each direction of the carriageway separately reflects this separation, and would restrict routing software from presenting illogical routing options (e.g. allowing U-turns along divided roads).

Please be mindful when reverting changes of this scale that you don't inadvertently damage route relations, as you did to bus routes through Maiden Gully.

Cheers

Spare me the selective quotes. This scenario is by no means the "default" for a roundabout in this "given jurisdiction". It is an edge case, and one which requires the turn restrictions in order for routing engines to correctly route vehicles through the intersection.

Slip lanes should be marked as _links per osm.wiki/Highway_link. If that causes issues with route hierarchy, the turn restrictions must be implemented. This does not contradict anything listed within the Relation:restriction article.

Implicit restrictions are not without precedent. They are mentioned (albeit not in detail) in the wiki page and wiki talk page you have linked. They also happen to be applied (as a 'no u-turn' rule) at each end of this very roundabout by a previous editor.

@daniel-j-h/diary/41777
https://labs.mapbox.com/mapping/mapping-for-navigation/implicit-restrictions/#mapping-implicit-turn-restrictions

Per Victorian road rules, a slip lane must be taken unless there is an obstruction. There is no requirement for a physical sign to mark this restriction, hence there is no sign.

https://www.racv.com.au/on-the-road/driving-maintenance/road-safety/road-rules/making-turns.html

Removing the road rules from the equation for the sake of the argument, missing the slip lane would require drivers to approach a left turn at roughly a 90 degree angle. That's almost certainly physically impossible given the nature of this junction.

Slip lanes are marked as highway links per osm.wiki/Highway_link. Routers need not fear about route hierarchy owing to the turn restrictions.

Hi. I have reverted this changeset to reinstate the turn restrictions. Drivers approaching the roundabout along Arthur Street in either direction must use the slip lanes to turn left into Power Street (eg. Arthur Street northbound into Power Street westbound, and Arthur Street southbound into Power Street eastbound).