It's the standard speed limit on highways in Italy. It can be lower when the road or its conditions suggest prudence.
It can also be 20 km/h faster on wide straight roads but I still have to see that. I guess nobody is risking the bad press after the first accident at 150 km/h.
The Coquihalla highway (BC-5) is notorious for it's steep hill and the speed limit is 120 km/h in ordinary conditions. I could probably find a lot of highways in BC that are similiar.
