I want to add a fence on top of my driveway. There is an 18 foot gap in between my garage and house that I would like to put a wooden fence into. The idea is put in a 12 foot gate with two side. One side would be 8 foot long on wheels only to be opened up when needed to drive through (truck, lawn tractor, etc.) The second side would be 4 foot for general walking through duties. Fencing in the rest of the yard with metal posts and fencing. The question is, without attaching the end posts to the house and garage, how would I attach the fenceposts into the concrete needed to create this gate? Any help would be greatly appreciated. I have done fencing before, but never over preexisting concrete.

You can do it a couple of ways, but with the weight, I'd use 6X6 PT and sink them in the ground 3ft. Put some #57 stone under the post, plumb the posts, support them and put hi strength redi mix in the hole. Let sit 2-3 days before attaching the gates.