Highway 17, along Lake Superior itself, has very little truck traffic. It mostly serves as a scenic route for travellers. Transports primarily take Highway 11 through the north because it is flat. All the hills and turns make Highway 17 too difficult for most transports.
It is an amazing drive though. From Duluth to Sault Ste Marie. The absolute best views are right around Nipigon (where they're building the cable stay bridge), at a place called Kama.
http://www.panoramio.com/photo/95666169
http://www.panoramio.com/photo/36323219
That's what your Rockies will look like in 1.2 billion years.
If they could make the entirety of Highway 17 3-lanes (alternating, like they currently do) with a barrier, that would probably be enough for that route. Highway 11 has a lot more space except for the stretch between Nipigon and Beardmore which runs through valleys, so it could easily be twinned. It's just a matter of cost. I'd rather see more freight shipped by rail, but the safety standards seem to be lagging more in that industry than in trucking. Within 20 years, the entirety of Highway 11/17 through the Lakehead should be twinned, if all the projects the Liberals have started actually get completed. For all their pro-car rhetoric, the PCs actually have a stronger track record of cancelling our highways as opposed to building them.