[Imports] Road data imports from CC0 government database for Sweden

[Anders Torger]

Hello,

The Swedish public directorate Trafikverket maintains a database of 
Swedish highways in a system called NVDB (the national road database). 
Trafikverket has had this database available to the public under the CC0 
license for since a fewyears. It has already been used informally by 
various local tech savvy Swedish mappers to speed up their own mapping 
by making their own translation scripts and sharing tips with others 
interested.

Now we want to formalize this process and make it more broadly available 
to our local mapping community.

The quality of Swedish highways in OSM varies a lot. The big cities are 
generally well covered, but looking at the whole country much of the 
data was mapped back when orthophotos had poor resolution and 
positioning, so there's low resolution geometries, often with large 
offset errors and missing roads here and there. In addition there's very 
little information tied to the roads, or even incorrect like maxspeed 
which has had nation-wide makeovers the past decade.

NVDB has all this data with very high quality. A Python script has been 
developed and tested in some pilot imports which converts the 
multi-layer shape-files delivered by NVDB to OSM-XML. The import itself 
is a completely manual process where the converted layer is loaded into 
JOSM and then merging workflow is used to upgrade and merge existing 
geometry and tags. This means that the import is very time-consuming, 
especially if there's a need to correct positioning of surrounding 
landscape and buildings, so this is expected to run over several years 
with low intensity.

To make it easier for less tech savvy mappers to participate we will 
provide pre-generated files for each municipality so it's not necessary 
for the mapper to set up the environment to run the Python script on 
their own.

This work has been in the open during the whole process and so far been 
discussed in the most popular informational communication channel in the 
Swedish OSM Community, which is a facebook group. It has been very well 
received, with a dash of the usual amount of healthy skepticism that any 
import effort generates.

Norway's counterpart to Trafikverket has also released a database 
(actually also named NVDB), and in the Norwegian OSM community this type 
of import has been formalized already and been ongoing for a while. We 
have got help and tips from them in designing our own import process for 
Sweden.

Here's a draft document of the import process: 
https://wiki.openstreetmap.org/wiki/Import/Catalogue/Sweden_highway_import

/Anders