Here's an updated representation of the "dog bone" roundabout proposed for Harrisville/Dieppe Blvd/Route 15 interchange (from your linked documents).
Sounds like some traffic chaos ahead.......
So, if "westbound traffic on Route 15, heading towards Moncton, will not be able to exit on to the Harrisville Boulevard exit ramp", does this mean that traffic from PEI/Shediac/NE New Brunswick headed for the airport will all have to keep on going inbound as far as the Dieppe traffic circle, before backtracking to the Dieppe Blvd turnoff? That's quite a detour! The airport authority should provide an update about this on their website.......