Here are my thoughts on the approach for setting up a test city:
Basically, it would be a test city A within a test city B, like a bubble within a bubble. The outer bubble (test city B) area would be say 50 to 100 square miles, and it can be square or rectangular. The inner bubble (test city A) would be round or octagonal as an enclave somewhere within the outer bubble of test city A. Each one would serve various purposes. The idea of test city A is to have the experimental homes, buildings, automation plants, high-tech farms, advanced transportation systems, cutting-edge learning facilities, state of the art entertainment facilities (movie theaters, pools, amusement parks, golf courses, tennis courts, etc.), the most advanced healthcare facilities, energy gathering facilities, etc., and the idea is to make it say 90% independent of resources and money from the outer bubble (once the basic foundation has been created).
The outer bubble, test city B, would be a city that's almost indistinguishable from any other modern day city, other than that its purpose is to facilitate test city A by basically providing a place for people working on developing it from the outside; it would have airports (one larger international and one smaller regional airport), farms, forests, lakes or ponds, gyms & athletic facilities, power plant, a police department, shops, restaurants, golf courses, hospitals, clinics, schools and universities, rail yard, warehouses, buildings, freeways and roadways, hotels, motels, etc. It would act as its own proving ground for simple things that make significant differences; it would say only be 5 - 25 % independent from the rest of the world (from resources, trade, money, etc.), but the idea would be to look for quick and easy changes that make it 20 - 100 % more efficient.
Part of the purpose of test city B is to provide test city A with some resources, like water and food from its own farms, and to act as a buffer between test city A and the "rest of the world," so that people who go to test city A are going there because they're curious and want to see & interact with it. There may still be some roads that go through test city A, but it would have far less roads than test city B; this would be to allow "passerby" tourists to check it out as they're driving by to their main destination. The freeways of test city B would just be set up so that as people drive outside the perimeter of test city A they can have a clear view of it from the freeway, from some distance, or they have to get off an exit to go into test city A. It would be geared to make transporation from test city B to test city A much easier if people park in test city B and take a high-speed monorail into test city A, though. This high-speed monorail would also take people to the airports and train station.
I'll add more and answer questions about the details I have in mind as the time comes. If anyone is skilled in some sort of 3D drawing app or simulator geared for drawing up images (such as Google Sketch) and would like to work with me to produce a "visual aid" for this 2-layer test city idea, please reply to this thread or send me a PM.
EDIT: I almost forgot to mention that the size of test city A would be about one fourth to one tenth in ratio to the area of test city B (and it doesn't have to be directly in the center of test city B).