[onewhippedpuppy]

My brother in law works for a market research company that does traffic studies. They are hired by DOTs all over the USA and Puerto Rico. From talking to him they do traffic surveys (pull people off of the road to ask them about their driving habits), GPS trackers in cars to observe driving habits, phone surveys, and those little car counters that go across the road. They try to paint the picture of who uses the roads, where they are going, if they are taking alternate routes to avoid certain areas, etc. Basically a comprehensive picture of who is using roads in certain areas and why. It's interesting work, of course how the DOT uses that data is out of their hands.