[1] The term hostile architecture is often associated with items like "anti-homeless spikes" – studs embedded in flat surfaces to make sleeping on them uncomfortable and impractical.
[4] Hostile architecture is also employed to deter skateboarding, BMXing, inline skating, littering, loitering, public urination,[5] and trespassing, and as a form of pest control.
[7][8][9] American urban planner Robert Moses designed a stretch of Long Island Southern State Parkway with low stone bridges so that buses could not pass under them.
[10][11] Outside of the United States, public space design change for the purpose of social control also has historic precedent: the narrow streets of 19th century Paris, France were widened to help the military quash protests.
[17] Beyond CPTED, scholarly research has also found that modern capitalist cities have a vested interest in eliminating signs of homelessness from their communal spaces, fearing that it might discourage investment from wealthier individuals.
[38][39] Jernhusen's press officer maintained that they "put in the armrests primarily to make it easier for the elderly and disabled to sit and stand up" but admitted in an interview that the perceived orderliness problems at the station building influenced how the benches were designed.
[48] Fences or grates are a common form of exclusionary design, often used to prevent access to places where there is protection from the elements, for example under stairs, bridges, or near fan systems that blow out hot air.
[49][50][51] In the spring of 2015, the City of Stockholm, Sweden, erected a 200,000 kr (~22,900 USD) fence to prevent homeless people from seeking shelter under a staircase in Kungsholmen.
[53][54][55] One example is when representatives of the New York City Subway announced via social media in 2021 that "benches were removed from stations to prevent the homeless from sleeping on them."
Other examples that have occurred include a stone painted in rainbow colours, putting out blocking shrubbery on a sidewalk, and "fun" shaped seating.
[73] Bonhams in San Francisco was criticised for an external sprinkler system that it claimed was used to clean "building and perimeter sidewalks during non-business hours intermittently over a 48-hour period", and which was also a point where homeless people gathered.
For example, Selfridges in Manchester installed metal spikes outside their store for the purpose of reducing "litter and smoking," which suggests hostile architecture may be implicated for one reason but explained by another.
[78][79] Some members of England's homeless community interviewed by researchers have noted that hostile design contributes to their displacement and feelings of insignificance, as it appears that local business interests are prioritized over their survival.
[19] Some forms of hostile architecture are easy to identify, while others could be interpreted as either exclusionary or non-exclusionary, such as spaced-out singular chairs constructed at a playground in Sweden, which may appear intentionally designed to dissuade homeless sleeping, or as an acknowledgement that Swedes consider it impolite to sit near strangers.
[80] Some researchers have said that hostile architecture should be evaluated within the wider context of the community, and should recognize the social and political forces motivating a particular design choice, such as anti-homelessness legislation or sentiments.
[59] As of March 2020[update], there has not been a wide-scale empirical study that has measured the impact of hostile architecture on the wellbeing of homeless people or other targeted populations.