A spate of mayors across the globe have spent the night sleeping rough in solidarity with their rising number of homeless constituents. Simultaneously, the built environment we occupy has been transforming to become more and more hostile to these very people.

Anti-homeless spikes and "hostile" benches have been cropping up across cities worldwide. However, keeping our field of vision sanitized from society's "unwanted" elements as we move from workplace to city to home will do nothing to address the roots of the problem. On the contrary, it simply moves the problem on, and in the process makes our urban spaces more and more divisive.

Finding space for the homeless

America's homeless population is one of the most prominent groups targeted by this new trend. As of 2016, there were approximately 550,000 homeless Americans. Homelessness is very much an urban phenomenon, and the worst offenders in the U.S. by far are New York City and Los Angeles, where 1 in 5 of the nation's homeless population lives. The homeless "hub" of LA's Skid Row lies at the epicenter of the crisis.

In recent years we have also seen a rise in the criminalization of homelessness in U.S. cities. City administrations have sought to stem the rising tide of street-sleepers by making sleeping in public spaces illegal, removing the homeless from public spaces rather than helping them to find alternatives to the streets.

Hostile architecture

Hostile architecture is the name given to a controversial trend in urban design that seeks to deliberately design urban spaces to be unpleasant — hence its other name, "unpleasant design." It is another tool that has been deployed globally to make certain spaces intentionally repellent to certain groups.

Infamous and eccentric examples from abroad include a planned park bench in China, where a coin-operated system means that after a certain period of time steel rods will pop up to eject the occupant. The Chinese bench was ironically inspired by artwork that a German sculptor designed as a protest against the commercialization of modern life.

However, most examples closer to home take a much more subtle approach.

Pavement corners shaped to deter skateboarders, spikes and bollards underneath bridges, dividers on park benches, high-pitched tones to repel teenagers or curved subway perches a host of options have been dreamed up. The Camden Bench, somewhat famous in the niche world of urban furniture, appears to be designed to deflect anything human that it comes into contact with.

Wasted lives

Critics argue that such tools turn our public spaces into "pseudo-public" places and physically entrench the already severe social divisions in our cities.

Polish philosopher Zygmunt Bauman who thought we should "see the world through the eyes of society's weakest members" believed modern society sees the homeless like refugees or the unemployed, as a disposable population. The "patient dumping" accusations on Skid Row and elsewhere are vivid depictions of his suggestion.

Bauman's "human waste" is exactly what these urban design tricks are seeking to hide from the view of the rest of us in a quest for order and "urban hygiene."

The costs of 'urban hygiene'

The exploitation of opportunities for social engineering through urban design is nothing new. But as cities become more and more heavily "designed," the opportunities to exclude targeted groups from certain spaces proliferate. Our urban spaces today are by no means accidental instead they can reveal a form of "considered unkindness" on the part of urban planners and city authorities.

Good urban design can, of course, help with crowd control and make our cities more efficient, but crucially the design tricks of hostile architecture are non-negotiable. There is also a deep inhumanity to pavement sprinklers that periodically spray the most vulnerable members of society.

One park in Vancouver has made the opposite gesture by providing benches that fold out into shelters for the homeless, and Copenhagen has dedicated space specifically for the homeless to bury their dead.

These two examples show how to confront the marginalization of the vulnerable rather than ejecting them from our field of vision.