[methodin]

I get that we want it to be consistent but having driven the same roads for years, in the same times of day, in varying but similar weather patterns the driving is completely sporadic so no amount of normalization well give you anything more than a crapshoot on any given day other than "it will probably take me anywhere from 20 to 50 minutes." Statistical analysis is great for many things but understanding the "now" of a traffic pattern is not one of them.

[privong]

I think it depends on what one wants to model. For a general understanding of how traffic flows, a statistical model is okay. On the other hand, if you want to know why a specific traffic jam is happening and how it's affecting the flow, a statistical model won't be sufficient.