The issue of hot summer temperatures causing the bitumen on roads to melt is covered in this story on the stuff website from a few days ago.
While having one of our occasional chats with Lee Amor of the Cruise Shop in Waikanae, he said that Asian countries have much hotter temperatures than we do but don’t have the problem of melting roads (Australia doesn’t either). When he asked someone in Downer why that was, the admission was, “Oh that’s deliberate, so that we can go and redo the surfaces.” In other words a guarantee of work. The compound used in NZ will likely melt over 33ºC ambient temperature.
That in our view is something that requires a government inquiry. We’ve already seen the problem of the ‘Ewy’ surface prematurely deteriorating, and while it is an incentive to use the railways instead, it is not good value for taxpayers.