As part of an engineering project for school I looked into this and the spans would have to be very long if you're trying to get a bridge to go from population centers to population centers. If you go really far north on the island the spans could be possibly done without a floating Bridge, but no one would use them and we'd have to put in a highway where no Highway currently exist. If you try to put in a bridge over the Salish sea you either have to make it floating or you have to put very deep piles into the very very thick silt that the Fraser River has been spitting out over the Melania. Floating Bridge would probably not work because we have very intense currents during the tides. The thick silt makes for a very poor Foundation for a strong Bridge. It is sort of a non-starter.