I'm always on the fence about speed limits. It seems ridiculous that in 2014 with car technology so far ahead of 50 years ago that we aren't allowed to drive any faster than then. Cars today are not only 1000x safer, but easier to drive at higher speeds.
But, then we have to factor the humans in. Are drivers any better? I don't think so. When I was just 16 I drove a 1981 Honda Accord from the Yukon into Alaska, into BC, to Alberta, and through Saskatchewan. A road trip of over 7000km. It was my first experiences on large urban streets and on multi-lane highways with large trucks, etc. One thing I noticed was the courtesy and safety of professional drivers. In the cities, people coped quickly and easily with my lack of local road knowledge. We moved to Edmonton in 1983 (the missus and me) and the same thing happened. I quickly adapted to urban driving, but was assisted by the general politeness of the drivers around me.
Fast forward 30+ years. Today our roads aren't much more capable of carrying more cars than we had here in 1983, but our city is more than 2x the size. Congestion and frustration combined with less desire to become a competent driver can be added to "license factories" that sell you a license and we have a driving environment that really sucks.
Highway 2 between Edmonton and Calgary is the exact same highway it was in 1983. With 4x the traffic volume. And with the change in economic climate and culture, people are trying to work on the road (laptop on the dash, etc) and are hurrying to get to their destination.
I rarely see cars being driven in a manner that makes me think "yeah, we could travel at a good clip." Most of the time, I think "my gawd, his/her license should be pulled."
Should we be able to have the divided highway limits in Alberta at 140? Yes. Even on the old roads, there's no reason why modern cars can't easily drive that speed. Could we? Not really. So few drivers can handle even that fairly low speed (compared to the capability of cars) that it would be insane. And the real problem? A winter's day where the road surface is really only good for 90-100, and of course, there would be a ridiculous number of people driving 145 "cause it's legal."
That said, 136km/h is NOT "super-speeding." We have people routinely clocked at 200 in our urban area on the freeway. Manitoba cops are easily outraged.