Perimeter Walls

Shenzhen's non-commercial sections are often enclosed by perimeter walls for privacy and security. What is understandably necessary in an urban fabric quickly devolves into entire sections of the city being closed off to public traffic. (The mix-use housing typology that provide for ground level commercial activities is noticeably missing at the bottom of high rises. Instead, peddlers' carts attack street intersections and a scattering of shopping malls sit on block-sized islands dispersed throughout the city.)

All perimeter walls have gateways and openings to let private passage through. These openings are often guarded by gatehouses and attendees. Like crossing a checkpoint, there is a protocol to follow before opening the gates for entry. These thresholds disrupt the flow on the sidewalk and interactions between the public passer-bys. The street becomes a maze of ugly walls.

The lack of public identity is one of the faults that I attribute to the over-zealous claiming of private spaces. Is there a better way to provide for security and a sense of public space? (Are there similar deterrents to monotony and rigidity of the perimeter walls and provide for a smoother transition between what is public and private?) Can architecture create a new "defensible space" for the city scale?