well, from that picture we can't really see how much of the highway was wrecked, as in the first picture it looks like the section near the horizon was relatively untouched (and in the second picture, if you look closer to the horizon, the shoulder of the road there wasn't re-paved either because it didn't need to be), so it may have just been a relatively small section near this hill that got wrecked.
beyond that, it's a reasonable amount of work to break the road fragments, dispose of them, level out the terrain and re-pave/paint it. Not that it's trivial by any means, but it should be doable in 6 days.
part of what makes road maintenance (especially on highways) take a while is that it's done during night hours when there isn't much traffic so as to reduce the impact it has on commutes, but if the road's already destroyed, you don't have to worry about that.
not to mention, when something important like a highway needs to be fixed it gets done quicker. :V