Well check this out:
We had to cut open a street a few weeks ago and this is how thick it was. Less than 1 inch and it had maybe 4 inches of base (i.e. gravel and other non-stuck together stuff). I will never understand how people can do such completely sloppy-assed work. I mean less than an inch of asphalt on a freaking road? Heck, my driveway is made out of 4 inches of reinforced concrete....
Yikes, just yikes....