Napartaq, I believe that the author of the article and those he is quoting are referring to the entire area of surface streets that one has to traverse when connecting to or from the Seward and Glenn Highways as "downtown" --- I don't think that anyone is suggesting that this traffic is moving through the literal downtown of Anchorage.  

Regardless of what one wants to call that area, it is a fact that the lack of a highway-to-highway connection in "downtown" Anchorage is a grievous bottleneck and weak link in the Anchorage road system, the resolution of which is (at least) four decades overdue.