This is exactly what Canberra, Davis, and Boulder have ... except theirs are "lanes". And I like that idea very much.

You can see a picture of the Canberra one on this site:
http://www.virtualtourist.com/travel...MISC-BR-1.html
(this is not my photo or site, so I'm not sure what all is on it, but it does have a great shot of the street)
http://p.vtourist.com/2675861-Pic_fr...llerybcbr2005-

I suggested (in letters, calls, documents, etc. etc. until I was blue in the face) paving the shoulders of some of the outlying roads within the city limits of Winnipeg when they were in the process of paving those streets anyway (one in particular was gravel for the first few years I lived there). They paved the road, but left the shoulders gravel. I just don't get it ... it's not like they had to widen the road or remove buildings or sidewalks ... all they had to do was to add a foot or two of pavement on either side of the road when they were out there paving it anyway.

If cities are that reluctant to spend the money for a tiny bit of extra pavement, there's no way they would go to all the trouble to build barricaded or completely separated lanes.