In San Francisco Chronicle

Advocates for homeless people refer to the planters as “hostile architecture” meant to push the homeless population out of sight. The strategy is far from new: For years, frustrated residents and business owners in San Francisco, and even the city itself, have turned to architecture to prevent encampments on the street — things like planters, boulders or rocky pavement, windowsill spikes, curved or slanted or segmented benches, or even loud music or sprinklers meant to prevent the unhoused from sleeping, sitting or setting up camp in certain public spaces.