There's been some talk about diverging diamond interchanges
on the national highways thread and after looking them up I think they are onto something. Basically in these interchanges it follows a standard diamond interchange pattern but the intersecting road reverses flow on the overpass. It sounds crazy but with good design it works extremely well for interchanges with high numbers of left-turns.
Article about one in Montana
• Video Link
Currently only Halifax would require innovative thinking like this in Nova Scotia. NSTIR currently operates ~12 diamond interchanges in Greater HRM. Of these one has a split three-way approach (Larry Uteck), one has roundabouts (Margeson), two have one-way approach (Wright Ave, Aerotech), one is planned to become a highway interchange (Glendale), and five don't have enough traffic flow to warrant this solution initially.
This leaves Burnside Drive and Lacewood as the possible candidates for this design. Both currently suffer from horrendous traffic jams and both have serious issues relating to left-turns. Burnside Drive might be too cramped for this because of the 90 degree turn onto Highfield Drive however IMO this would be great for Lacewood. Throw in some bicycle lanes and proper sidewalk infrastructure and the notorious Christmas traffic jams will disappear overnight.
IMO NSTIR should use a mix of diverging diamond, standard diamond, roundabouts, parclos, and whatever 111/118 is in their interchange designs around Halifax. They can even evolve in that order (provided space is available).