WHy don't they do the thick concrete for road construction nationwide (at least on interstates)? I know down in Louisiana they do, and they don't have to do much road work other than lane widening or bridge work but once every ten years or so, even with all the trucks on the road. This asphalt stuff may be cheaper, but I think with all the $$ poured into that, it would save to do concrete.
In areas where ther is no frost, the thick concrete highways are great (unless you are on expansive clays, another story). Mnay of the older highways here in New England are concrete, but because of years of road salt, the concrete gets degraded and chewed up. Asphalt pacthing/overlaying is a cheap, effective and nearly permanent fix.
Also, frost heaves cause a slight lifting of the individual slabs, making for a bumpy ride and drastically shortening the roads life.