[ccurtsinger]

Minnesota does a significant amount of research on road surface materials. There is a section of I94 northwest of the Twin Cities that has three segments of highway, and traffic can be diverted onto one of the segments to test new road surfaces. Here's the MN DOT site with some test videos: http://www.dot.state.mn.us/mnroad/testcells/mainline.html (thrilling stuff).

Now that I'm in MA, I have heard several people say that concrete highways do not last through the winter, despite the large number of concrete-type highways in good condition in MN. Maybe this is the result of careful local road surface research? Roads are certainly better in MN than they are in MA, even though MN has colder and snowier winters. That could just be anti-highway spending sentiment from the big dig though...

[kevinr]

Another Midwesterner transplant to MA here -- colder in the winter is actually better for highways. Up and down around the freezing point all winter like Massachusetts does produces massive frost heave that Minnesota roads just don't need to contend with.

[douche]

Building good road-bed underneath helps enormously. Comparing the roads in Maine and Quebec, in Maine it's a mess of frost-heaves and constant repavement. In contrast, the Canadians rip up an old road down to ledge and build back a solid foundation - when a section of road gets rebuilt, it lasts 15-20 years.

[bkjelden]

I had always heard that ND had all concrete interstates (the only state with no asphalt interstates, in fact) because of the harsh winters.