This one has armrests to prevent you from dozing off.

Here's another — again with the arms, the stiff metal.

And this one — it's brand new .

The MTA in New York began installing them as part of a subway enhancement plan.

And they don't call it a bench.

They prefer the term "leaning bars."

So what if i told you it was designed with discomfort in mind?

New York City is filled with some of the most innovative architecture and urban planning in the world.

Today, nearly every kind of public space here has been developed with close attention to detail.

So these benches are no mistake.

They are designed to allow you to sit but not get too cozy.

And that is intentional.

The concept stems from a school of thought that goes by many names, but today we'll use "defensive design."

Defensive design is about moderating behavior.

The goal is to limit the ways an object can be misused.

These benches have armrests because that will prevent anyone from laying down.

Their short back is another nod to say, "This bench isn't yours forever."

This trend is worldwide.

And it's not just in the benches.

When you start looking for defensive designs in New York City, you'll find examples everywhere.

It's the presence of security cameras in subway turnstiles or Times Square.

It's these spikes on this column, meant to deter birds.

It's the knobs on these ledges, meant to discourage skateboarders.

And there were once sprinklers underneath the awning of this bookstore, to prevent people from sleeping there.

It's sidewalk barriers.

It's even these regular streetlights.

Streetlights are probably some of the most recognizable defensive designs.

When they surfaced in the 19th-century Western cities, the dynamic of urban life changed.

Because of them, more people spent time outside at night, which drove economic development and a reduction in crime.

Most hostile architecture tries to influence behavior in a similar way.

The designs attempt to make public space a bit more hospitable, more ideal.

Defensive designs can deter crime.

It can prevent the destruction of public property.

And it can prevent loitering.

But there is a reason why defensive design is characterized as "hostile."

Take the example of the leaning bar.

Disability advocates have a problem with that appearing in the MTA.

One advocate pointed out that "People who travel who have disabilities or just get tired sometimes need a bench to sit on, not a wall to lean against."

And while no one likes an uncomfortable bench, these additions mean something more for people who are experiencing homelessness.

The United States is currently experiencing a decline in the overall homeless population.

But in New York city, the number of homeless people is growing.

About 1800 people were found to have been sleeping in the subway.

That's because emergency shelter isn't always a viable option.

There are several examples of hostile architecture that target people who are homeless.

These designs imply that public space is not where homeless people should be.

As it goes, city planners have a dilemma — how do they design inclusive cities?

As for the enhanced subway initiative, the MTA's mock designs highlight new USB ports and electronic signage in stations.

But you won't find any press materials highlighting this uncomfortable bench.

Excuse me, the "leaning bar."

That's because it makes for an uncomfortable discussion about who we design public space for — and who gets left out.