Funny is that I've been to Navteq presentation of the TMC system here in Brazil like 2 years ago and they announced 4 sources to provide traffic data:
- Radio Sul America Transito: local (Sao Paulo area) radio which count on listeners traffic info and with Maplink as well);
- G.E.T.: official traffic management company (pretty shitty info, barely of the main roads);
- Tracking system: most of private insurance companies install tracking system in vehicles, that info is gathered by Navteq. They mentioned also a 'double check' in order to avoid not to think that a parked car is stucked in a traffic jam;
- Human: Navteq agents in the main roads monitoring traffic with their own eyes :D
Seems that is not working the way they promised... what a pity.