Hmm, I thought everyone used San Jose.
The Old St Augustine Road interchange exit from 95 southbound is terribly short and requires very sudden slow down, unless you want to fly into the onramp for 95 southbound.
Also, the main reason why is because the limited number of interchanges on 95, especially 210, are critically over built and needs better access to US1. A good bit of the traffic problem would be releaved, for a few years at least until developers come along, by building an interchange with Racetrack Road. So, you either go through Bartram Park and sit, or take San Jose and sit.
9B is not necessary, mass transit is. JTA buses do not go into St. Johns County at all, and that's likely part of the problem. St. johns County has ZERO mass transit options, and building another highway is not the answer. You have a perfectly fine and easily accessible railroad track adjacent to main road in the county that can be utilized.
The way the communities in the northern part of St. Johns and southern Duval are built or spread far apart to not even utilize connectivity. BPB is NOT an example of connectivity in action. I've said it before and will say it again, connectivity via a street grid can do wonders.
Take Oklahoma City for example. They have a perfect grid pattern, and to travel from Norman to downtown OKC using city streets alone takes only about 45 minutes for a 20 mile trip, roughly the same distance from most locations in northern St. Johns to downtown Jacksonville. Part of the problem though is our greatest asset, the river.