We want to install a wood fence on top of a 4", 3000 psi wire meshed concrete driveway. I want to hold the 4" posts up using base plates that are made of approximately 1/4" or thicker steel. The square base plate I thought would be about 10" X 10". And a welded on socket for the post to go into would be about 10 inches tall. A horizontal bolt would hold the post in place in the socket. I will anchor the plates to the concrete with 1/2" or larger bolts.
Does this set up sound ok? Will it eventually cause the fence to wobble side to side in the sockets? Would it possibly break the concrete out even though no posts will be near any edge. Do the base brackets sound ok?
The only potential problem I can see is wind. I would alternate the pickets on each side of the rail. This allows the wind to pass thru the fence. This design does allow for viewing thru the fence if you are close though. Cars or pedestrians passing by would have a difficult time seeing thru it. I would drill a hole on three sides of your socket. Weld a nut over the hole. This will give you a setup similar to a Christmas tree stand. By inserting bolts in the nuts it will allow you to adjust the post to plumb it.
The trouble with this design is that unless the posts fit really snugly into the base plates they will wobble and you'll need at least 2 bolts for each post.
You also haven't said how tall the posts will be or whether they will be wood or steel. To prevent rusting those base plates will need to be galvanised or made of stainless steel as will the bolts. The appearance of them may not be too flash either.
I think a better option that would be cheaper actually is to hire a concrete cutting saw and cut square sections out for the posts in your concrete driveway. Then dig down about 1/3 the depth of the post. And set your posts into new concrete poured into those holes.