I fully agree with rogbus, waze is already the best app for traffic information, and not only in Stockholm.

Some competitors that you may consider doing partnership with:
Google: Traffic information now works in Sweden.
Trelicity: http://www.trelocity.se/ http://www.dn.se/sthlm/trafiklaget

Then again, there are some functions that waze don't have, i.e. for road work...
In my opinion, TMC would add some great value to the Waze functionality:
Swedish road authority homepage (translated from swedish to english with google translate) and the English version with less information

Trafikverket is the authority responsible for gathering and manifest the information.

https://rdt.vv.se/rdt/AF06_Search.aspx

Svensk trafikföreskriftssamling / Transportstyrelsen

Here you can find information about onewayroads, through traffic, walking trails, charging for electric vehicles, maximum weight and much more. In Navteq we can set a road as trucks forbidden or taxi allowed. Hopes we can do it in Waze soon. Sorry for my english. Very sorry.

For the biggest cities you have...

http://trafiken.nu/sv/Stockholm/Sidhuvu ... n-english/

The best source for traffic information is probably http://www.trafikverket.se.

They have a subscription service but unfortunately I can only find those pages in swedish.

Here are a two links through Google translation:
http://translate.google.com/translate?h ... rmation%2F

http://translate.google.com/translate?h ... h-avtal%2F

The traffic data is also viewable on a interactive map
http://trafikinfo.trafikverket.se/lpvme ... .htm#id=15

I must say, your priorities are very confusing. Since Waze, at least in Stockholm, IS already the best traffic information source, why put effort into intergrating an extrenal information source, when basic functionality is still lacking, such as routing over long distances? Also, IRL some traffic disturbances and closures are scheduled/known in advance, but there is no way to schedule them in the map editor. There are even roads in Stockholm that only permit entrance at certain times of the day.That is the only kind of traffic information that Waze lacks and you should focus on if you ask me.

The public radio channel 'P4 Stockholm' gathers information from listeners (who dont know what Waze is or have no smartphone) . They also make RDS/TA announcements.

http://sverigesradio.se/sida/trafik.aspx?programid=2859