We describe a vehicle traffic analysis tool that implements an algorithm which estimates truck volume on highways. We used it to experiment with a data streaming abstraction called Infopipes, which seek to make data streaming applications easier to write. Most of the application is written in Smalltalk/X and the rest is written in Squeak. Smalltalk/X does the data processing, while Squeak provides the visualization. The two communicate by streaming data through Infopipes.