The design shown is clearly not compatible with letting normal drivers on it for safety reasons as much as anything else.Sure, thats what they say. But by building it for vehicles, all it takes to allow all cars to use it is changing a sign.
The road intersection on the Atlantic side means it wouldn't accomplish much of anything with private traffic utilizing it.
If it was just a basic, narrower, bike/ped bridge to make a connection without any of the fanfare, sure. The huge thing being shown? Probably not so much.It would be many times cheaper if it was designed only for peds, because you wouldnt need to support the weight of heavy vehicles.
A dense crowd of people weighs as much or more per sq ft than vehicles typically do. Your typical pedestrian bridge doesn't need massive supports and girders because it's narrow (in relative terms) and can't physically hold that many people for a unit of length.
But this thing as proposed has lots of space and is theoretical social space that you can very much expect will someday have a crowd of people shoulder to shoulder, whether that's for fireworks or an arts event, or whatever.
It'll have to be built to hold probably as much or more total weight than if it was a vehicle bridge. It'll certainly get far less wear and tear and need less maintenance/repairs by not seeing vehicle traffic, but I'm not sure that you save much on construction.