Thanks for the detailed description, now I'm pretty sure you run the same system like AU, getting shields only from primary streetnames following a predefined pattern. You'll have to define patterns for each possible shield, so currently it might be:
State Hwy x
State Hwy xx
State Hwy xxx
For getting a shield for 98a an additional pattern is required:
State Hwy xxa
PhantomSoul wrote:Hopefully Waze will expand its shield pattern recognition to include these in the near future.
Well, Waze will wait for you to give them the patterns, they don't get active themselves on this.
As I understand US community structure you run each state as Europe runs a country. For shields are a country function, you will have to coordinate a pattern-table US-wide.
To show an oval sign for SR26 you need either recode the name to State Hwy 26 or submit a pattern SRxx. Guess you will have to decide which way to go not case by case but national.