It has recently come to our attention that in the past week or two Waze has altered the algorithm used to determine the Best Continuation at a fork in the road. This was first posted about in the wiki update thread, but I'll leave that thread for discussing the upcoming necessary changes to the wiki to reflect this change. I'm creating this thread to alert other editors to this fact, which is already causing lots of URs.

In short: the algorithm looked for a match from the segment preceding the junction, to either of the segments after the junction. It first checked for a matching primary name, if it didn't find any it then checked for matching segment types. If a match was found that was the Best Continuation, otherwise both segments would get an instruction.

The good news:
The Best Continuation is only a factor when 2 or more segments leave a junction at less than 45° turn angles. (e.g. a fork in the road, an exit from a highway, a Wayfinder, etc.) This has no effect on turns which would give a "turn right/left" instruction, only ones which would give a "keep/stay/exit right/left" instruction. For a clearer understanding of the whole Best Continuation topic, please read the wiki page linked above.

The other news:
Alternate names now play a role in factoring which segment will be the Best Continuation! This is a very recent development, and can cause many highway exits, wayfinders, and road splits which were previously giving the proper instructions to have suddenly either stopped giving an instruction to a segment which needs one, started giving an instruction to a segment which is the clear continuation and doesn't need one. We still do not fully understand the full extent of this change, and how different variables are being taken into consideration in the algorithm. There is extensive testing underway (which will be documented in the wiki update thread) to determine all these variables.
What we have tested thus far, the following matches will be BC in order of preference:

• Two primary names AND their road types
• Two alt names AND their road types
• Two primary names only
• Two alt names only
• When there is any alt name on the preceding segment, there can be a cross-match between an alt name and a primary name (the alt of one segment matches the primary of the other)
  • If one side is a primary match, and the other is an alt match and a road type match, the side with alt and type match is BC (This is the first time we have seen a primary name match not be the BC)
  • When there is no alt name on both segments in a pair, alt names are not considered for matching
  • City names do not seem to affect this at all
  • There is no preference given to the order of the alt names

EDITED list for clarity

What do you need to know for now.
If you see URs, complaining of this behavior, please investigate them carefully, run the route through Livemap to be sure if the instruction has now changed, even if all the segment names appear correct in WME. Bear in mind that any Continue instruction shown in Livemap with a straight arrow is NOT given in the client. If you find a problem caused by this change, please don't edit anything, and post the PL to this thread so we can investigate it to help us learn the full extent of this change. After reviewing it, we will fix it to make it work properly again.