[Talk-se] Secondary and tertiary country/regional roads

[Thomas Fischer]

Hello,

I have a question about how to best/correctly map secondary and
tertiary country/regional roads ("länsvägar").

To start, I just want to recapitulate the street hierarchy in
Sweden. Please correct me if I am wrong here.
1. "Europavägar" have highest precedence. Naming consists of the
letter E followed by a number, always less than 100.
2. "Riksvägar" have no letters, only numbers, always less than
100.
3. "Primära länsvägar" have no letters, only numbers, in the
range of 100 to 499; ways keep their numbers across regional
borders.
4. "Sekundära länsvägar" and "tertiära länsvägar" have letters
("länsbokstavar") followed by numbers starting from 500; ways
change numbers at regional borders. The same numbers, albeit
with different preceeding letters, may be used in different
regions.

Now, I have observed that the data in OpenStreetMap is
inconsistent on using letters for category 4 roads. Looking at
http://www.openstreetmap.org/#map=13/62.9046/18.3360
you see some ways with regional letter (Y) and some without.

Unfortunately, category-4 roads do not have their full number
spelled on signs. Even worse, Trafikverket and other agencies do
not use regional letters in their public communication (e.g. "We
are re-building way 1234 near XXX"). The Swedish Wikipedia has
lists of regional roads, but it is unclear if those lists are
correct or complete.
https://sv.wikipedia.org/wiki/Kategori:Listor_%C3%B6ver_l%C3%A4nsv%C3%A4gar_i_Sverige

So, my questions are:
- Which official sources can be used to retrieve the official
  numbers for category-4 roads (remember, no signs in most
  cases)? Preferrably which real-world streets constitute given
  regional road.
- As an OSM mapper, should I include the letter ("Y 839") or
  omit it ("840", context information necessary)?
- Should any of the four categories of roads stored as relations
  (powerful but complex) or as regular "ref" tags on ways
  (simple but may has limitations)?

Thank you in advance!

Bye,
Thomas