It is funny because fashions in traffic planning have gone back and forth over the years. There were some large roundabouts built in the Halifax area starting in the 1940s or so. Of course, by the 1970s and later they were heavily congested and the roundabout design itself acquired a bad reputation. The Armdale Rotary still exists but the Micmac Rotary was replaced with a highway interchange.
Armdale. One of the problems here was that prior to 2005 cars
entering the rotary had the right of way. They added reversing lanes to the nearby streets but it still just handles too much traffic and it's a big pain at rush hour. It's also annoying for pedestrians to cross.

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The old Micmac Rotary.

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Newer Highway 111 interchange in Dartmouth that replaced the Micmac Rotary

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Halifax also has a bunch of complicated intersections where 3 or 4 streets meet in older parts of the city, and roundabouts have been suggested as an improvement for those areas. I'm not sure if anything will come of it, but I think they'd probably be an improvement.