  The availability of Open Government Data (OGD) provides means for citizens to
understand and follow governmental policies and decisions, showing evidence of
how the latter have contributed to both the place they live in and their lives.
In such a scenario, one of the proposals is the use of visualizations to
support the process of data analysis and interpretation. Herein, we present the
use of three different visualization tools, a commercial one and two academic
ones, applied to two specific Brazilian cases: the implementation of the Drink
Driving Law and the construction of a new overpass in an important city avenue.
Our focus was on the analysis of how visualization could help in the
identification of the effects of such traffic public policies. As our main
contributions, we present details on the effects of the observed policies, as
well as new cases showing how visualization tools can assist users to interpret
OGD.
