Here's the traffic count data for I-5 at Market Street:
It shows a slight uptick. (The x- and y-axis are the same as the bridge graph below.)
Here's total miles traveled per person (a rate, not a count do note!) in Oregon.
(Graph: Impresa Consulting)
As a rate it shows a significant decline off the trend.
Here, for comparison's sake, is the bridge traffic across the River.
Bridge crossings have shown the same plateau and decline that total miles traveled have, so the slight uptick on I-5 is interesting and ambiguous.
Rival interpretations of the data will be one of the sites of contention as we debate the need for a very large highway style bridge. Here rates and absolute counts are intermixed. (At my fingertips I don't have an exact apples-to-apples comparison.) It will be interesting to follow this and to learn more about it.
Update, mid-day Sunday
Data! Thanks to Gary in the comments for pointing out more context and comparative data. Here's an updated graph with traffic on the bridges, and two locations on I-5, the Market Street interchange that's discussed in the article and the Battle Creek - Sunnyview interchange on the southern edge of town.
Only the Market Street shows an increase.
Update Dec 8th, 2012
|Data from the Federal Reserve|
Driving and Recessions do not correlate
This change is structural, not cyclical
Matthew Yglesias at Slate