From Mike Davis’ Beyond Blade Runner: Urban Control, The Ecology of Fear, 1992:

The current obsession with personal safety and social insulation is only exceeded by the middle-class dread of progressive taxation. In the face of unemployment and homelessness on scales not seen since 1938, a bipartisan consensus insists that the budget must be balanced and entitlements reduced. Refusing to make any further public investment in the remediation of underlying social conditions, we are forced instead to make increasing private investments in physical security. The rhetoric of urban reform persists, but the substance is extinct. Rebuilding LA simply means padding the bunker.

As city life, in consequence, grows more feral, the different social milieux adopt security strategies and technologies according to their means. Like Burgess’ original dart board, the resulting pattern condenses into concentric zones. The bull’s eye is Downtown.
In another essay I have recounted in detail how a secretive, emergency committee of Downtown’s leading corporate landowners (the so-called Committee of 25) responded to the perceived threat of the 1965 Watts Rebellion. Warned by law-enforcement authorities that a black inundation of the central city was imminent, the Committee of 25 abandoned redevelopment efforts in the old office and retail core. They then used the city’s power of eminent domain to raze neighborhoods and create a new financial core a few blocks further west. The city’s redevelopment agency, acting virtually as their private planner, bailed out the Committee of 25’s sunk investments in the old business district by offering huge discounts, far below market value, on parcels in the new core.

Key to the success of the entire strategy (celebrated as Downtown LA’s `renaissance’) was the physical segregation of the new core and its land values behind a rampart of regraded palisades, concrete pillars and freeway walls. Traditional pedestrian connections between Bunker Hill and the old core were removed, and foot traffic in the new financial district was elevated above the street on pedways whose access was controlled by the security systems of individual skyscrapers. This radical privatization of Downtown public space - with its ominous racial undertones - occurred without significant public debate or protest.

Last year’s riots, moreover, have only seemed to vindicate the foresight of Fortress Downtown’s designers. While windows were being smashed throughout the old business district along Broadway and Spring streets, Bunker Hill lived up to its name. By flicking a few switches on their command consoles, the security staffs of the great bank towers were able to cut off all access to their expensive real estate. Bullet-proof steel doors rolled down over street-level entrances, escalators instantly stopped and electronic locks sealed off pedestrian passageways. As the Los Angeles Business Journal pointed out in a special report, the riot-tested success of corporate Downtown’s defenses has only stimulated demand for new and higher levels of physical security.