Most of these twinned highways on the prairies look like quasi freeways to me, with an even higher speed limit than full-blown freeways in Ontario and Québec. From what I've seen there are very few traffic lights on twinned highways outside cities like Regina or Saskatoon. Judging from street view and Google Earth there seem to be only two traffic lights between Estevan and Regina (both in Weyburn). That corridor will also be twinned to four lanes.
I think expressway explains the twinned highways more. A few traffic lights scattered, and many stop sign level at-grade crossings. Most rail lines are underpass or overpass.
The Trans-Canada in Regina still has about 5-6 traffic signals. I really wish that part was fixed up, but I guess with the new bypass being built around the city, it should make traffic better on that side.
Manitoba (in part of population I guess) has many more traffic lights on the Trans-Canada than Saskatchewan. That being said, work is
apparently being done upgrade sections west of Winnipeg, including the installation of four new overpasses.
One will be over the Yellowhead (Highway 16) and the Trans-Canada. I haven't seen any work yet though, so I'm starting to wonder if it got delayed or cancelled outright. There is also the Perimeter Highway in Winnipeg that consists of many traffic lights; too many for me to count. The whole thing should be upgraded to freeway IMHO, but I know that would cost quite a bit. Not to mention the fact that people who live there (AKA me) don't use the highway very often. With expansion though (there are new houses that keep creeping closer to the highway), I could see it happening in 20 years.
EDIT: Yup, cancelled outright. Good ol' Manitoba.