@cicerone imposter,
I thought it was a fairly stupid article - typical Krugman stuff. As an ecpnomist he can do the math but I doubt that he really ubderstands what the numbers mean.
Government bureaucracies aren't very good at delivering large construction projects on time and under budget. This has beem amply demonstrated over many years. Moreover, the states are usually far better (or less bad) than the Federal government at all this, and that's how the interstate system was launched under President Eisenhower - basic Federal specifications for a few elements of road design and Federal Grants to the states for implementation.
Even that system was done in imitation of earlier state and local efforts, notably including the Pennsylvania Turnpike, development of which started in the early 1930s and which followed even earlier local turnpikes in that and other states.