Traffic on the ODOT network in Portland peaked in 2002, according to ODOT traffic counting.  When the Alaska Pipeline shuts down due to low flow (due to depletion - geology) traffic jams won't be much of a concern.  The pipeline is being scaled back in the summer so there is still enough flow to function in the winter.  

Admittedly, most of the citizens objecting to this boondoggle aren't focused on energy and geology.