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One of the common criticisms of new housing is that it's designed for rich people and that it does nothing to help the housing situation of average citizens. The YIMBY response to this is, "Well, yes, it does actually, because supply eases overall housing pressures and because of the filtering effect." This is the process whereby housing becomes gradually more affordable and available to people as new housing is built and vacancies are created. But most people don't like this explanation. It feels slow and indirect.
Here's something that might help.
In this recent study, researchers looked at the downstream effects of a new condominium tower in Honolulu called The Central Ala Moana. Completed in 2021, the building contains 512 units, of which 60% are income-restricted (310 units) and 40% are market-rate (202 units). It was developed under a state affordable-housing program that gave the developer height and density bonuses, plus fee waivers totalling about $13 million in exchange for delivering income-restricted units. (In my opinion, this is directionally preferable to unfunded inclusionary zoning mandates.)
Using address-history microdata, the researchers tracked who moved into the new condominium tower, and constructed detailed vacancy chains across multiple rounds of moves. Here's what they discovered:
Among documented vacancies, the 202 market-rate units produced 87 downstream vacancies (0.43 vacancies per initial unit), while the 310 income-restricted units produced 90 (0.29 vacancies per unit). Thus, market-rate units are more likely to generate a downstream vacancy. The main mechanism is new household formation: movers into income-restricted units are more likely to be a newly formed household, leaving family or roommates at the prior address and thus preventing a vacancy from being created.
In absolute numbers, they found that the completion of the building induced more than 500 local vacancies in the three years after construction, by setting off a chain of moves. Importantly, the researchers also found that the homes being vacated were, on average, about 40% less expensive than those in The Central. So even though a new building may be more expensive than the existing housing stock (which is generally the case or else the development wouldn't happen), it does generate benefits.
It eases overall housing supply constraints and expands affordability in the local housing market.
Cover photo by Michael Olsen on Unsplash
One of the many differences between Canada and the US is that our roads are less deadly. A new study by the US Insurance Institute of Highway Safety and the Canadian Traffic Injury Research Foundation found that between 2010 and 2020, total road deaths in the US rose 18%, while in Canada they declined 22%.
This "crash gap" also widens when you look at deaths per vehicle mile driven (as opposed to per capita), which should, in theory, normalize the fact that Americans tend to drive more on average than Canadians. So why might this be? Both countries are broadly car-oriented, at least compared to the rest of the world.
The study presents a number of possible explanations: Canada has stricter drunk driving laws, Canada uses more traffic cameras, Canadians are relatively poorer and therefore drive less, Canada has higher gas taxes (which discourage driving), and the list goes.
But my unproven theory is that a lot of this gap can be explained by differences in the built environment. Solutions like traffic cameras are, to give just one example, what you do when you've failed to design the road you actually want. They're patches, not fixes.
The root problem is the design of the road itself, which is why New Yorkers are only about a third as likely to die from a transportation-related accident compared to the average American. Why? Because it's an urban place designed around non-car mobility.
Conversely, this is also why the top 20 most deadly metro areas in the US for pedestrians are in the south, as opposed to in older northern cities. And it's because these tend to be newer car-oriented metros.
So when it comes to Canada vs. the US, I suspect that much of the gap can be explained by differences in the physical environment and higher transit usage north of the border. It probably also explains why Canada is safer than the US, but not safer than Europe when it comes to transportation-related fatalities. We're simply not urban enough.
The simple takeaway is that the more you optimize your environment for cars, the more dangerous you make it for humans.
That said, this is likely to change with the continued adoption of autonomous vehicles. We can (and should) debate whether it's prudent to plan our cities around them, but I think there's little doubt that we'll see road safety increase dramatically.
Chart via CityLab
Here is an interesting study that looked at the impact of urban highways on social connections within the 50 largest US cities. To measure this, the researchers used Twitter data from 2012-2013, which is a period of time where the default setting in the mobile app was to tag each tweet with the user's precise geographic coordinates.
This allowed the team to generally figure out where a user is likely to live. If you're often tweeting from the same residential address, then there's a good chance that's home. They then looked at things like mutual followship as a measure of social ties. And what they ultimately found was that in all 50 cities, urban highways exhibit a strong barrier effect. They measured this using something they call a "barrier score."
One of the common criticisms of new housing is that it's designed for rich people and that it does nothing to help the housing situation of average citizens. The YIMBY response to this is, "Well, yes, it does actually, because supply eases overall housing pressures and because of the filtering effect." This is the process whereby housing becomes gradually more affordable and available to people as new housing is built and vacancies are created. But most people don't like this explanation. It feels slow and indirect.
Here's something that might help.
In this recent study, researchers looked at the downstream effects of a new condominium tower in Honolulu called The Central Ala Moana. Completed in 2021, the building contains 512 units, of which 60% are income-restricted (310 units) and 40% are market-rate (202 units). It was developed under a state affordable-housing program that gave the developer height and density bonuses, plus fee waivers totalling about $13 million in exchange for delivering income-restricted units. (In my opinion, this is directionally preferable to unfunded inclusionary zoning mandates.)
Using address-history microdata, the researchers tracked who moved into the new condominium tower, and constructed detailed vacancy chains across multiple rounds of moves. Here's what they discovered:
Among documented vacancies, the 202 market-rate units produced 87 downstream vacancies (0.43 vacancies per initial unit), while the 310 income-restricted units produced 90 (0.29 vacancies per unit). Thus, market-rate units are more likely to generate a downstream vacancy. The main mechanism is new household formation: movers into income-restricted units are more likely to be a newly formed household, leaving family or roommates at the prior address and thus preventing a vacancy from being created.
In absolute numbers, they found that the completion of the building induced more than 500 local vacancies in the three years after construction, by setting off a chain of moves. Importantly, the researchers also found that the homes being vacated were, on average, about 40% less expensive than those in The Central. So even though a new building may be more expensive than the existing housing stock (which is generally the case or else the development wouldn't happen), it does generate benefits.
It eases overall housing supply constraints and expands affordability in the local housing market.
Cover photo by Michael Olsen on Unsplash
One of the many differences between Canada and the US is that our roads are less deadly. A new study by the US Insurance Institute of Highway Safety and the Canadian Traffic Injury Research Foundation found that between 2010 and 2020, total road deaths in the US rose 18%, while in Canada they declined 22%.
This "crash gap" also widens when you look at deaths per vehicle mile driven (as opposed to per capita), which should, in theory, normalize the fact that Americans tend to drive more on average than Canadians. So why might this be? Both countries are broadly car-oriented, at least compared to the rest of the world.
The study presents a number of possible explanations: Canada has stricter drunk driving laws, Canada uses more traffic cameras, Canadians are relatively poorer and therefore drive less, Canada has higher gas taxes (which discourage driving), and the list goes.
But my unproven theory is that a lot of this gap can be explained by differences in the built environment. Solutions like traffic cameras are, to give just one example, what you do when you've failed to design the road you actually want. They're patches, not fixes.
The root problem is the design of the road itself, which is why New Yorkers are only about a third as likely to die from a transportation-related accident compared to the average American. Why? Because it's an urban place designed around non-car mobility.
Conversely, this is also why the top 20 most deadly metro areas in the US for pedestrians are in the south, as opposed to in older northern cities. And it's because these tend to be newer car-oriented metros.
So when it comes to Canada vs. the US, I suspect that much of the gap can be explained by differences in the physical environment and higher transit usage north of the border. It probably also explains why Canada is safer than the US, but not safer than Europe when it comes to transportation-related fatalities. We're simply not urban enough.
The simple takeaway is that the more you optimize your environment for cars, the more dangerous you make it for humans.
That said, this is likely to change with the continued adoption of autonomous vehicles. We can (and should) debate whether it's prudent to plan our cities around them, but I think there's little doubt that we'll see road safety increase dramatically.
Chart via CityLab
Here is an interesting study that looked at the impact of urban highways on social connections within the 50 largest US cities. To measure this, the researchers used Twitter data from 2012-2013, which is a period of time where the default setting in the mobile app was to tag each tweet with the user's precise geographic coordinates.
This allowed the team to generally figure out where a user is likely to live. If you're often tweeting from the same residential address, then there's a good chance that's home. They then looked at things like mutual followship as a measure of social ties. And what they ultimately found was that in all 50 cities, urban highways exhibit a strong barrier effect. They measured this using something they call a "barrier score."
Now this sounds right and supports lots of other evidence that highways divide cities; but Twitter isn't necessarily a place where mutual followship means you actually know the person in real life and you regularly walk down the street to see if they can come out and play. So one of the things that the researchers also did was work to replicate their findings using data from another social network called Gowalla.
I very vaguely remember this platform, but it is/was a social network where users are supposed to connect with people they actually know and share their locations through check-ins. With this data they found that their "barrier score" was even more pronounced, which makes sense given that the platform's social graph should have had, in theory, stronger real-life ties.
But even if you don't believe the social data, these results should make intuitive sense. Highway underpasses and overpasses tend not to be the best environments for pedestrians. They're usually a clear break in a city's urban fabric, which can make people second guess whether they really want or need to cross it.
Cover photo by Tom Barrett on Unsplash
Now this sounds right and supports lots of other evidence that highways divide cities; but Twitter isn't necessarily a place where mutual followship means you actually know the person in real life and you regularly walk down the street to see if they can come out and play. So one of the things that the researchers also did was work to replicate their findings using data from another social network called Gowalla.
I very vaguely remember this platform, but it is/was a social network where users are supposed to connect with people they actually know and share their locations through check-ins. With this data they found that their "barrier score" was even more pronounced, which makes sense given that the platform's social graph should have had, in theory, stronger real-life ties.
But even if you don't believe the social data, these results should make intuitive sense. Highway underpasses and overpasses tend not to be the best environments for pedestrians. They're usually a clear break in a city's urban fabric, which can make people second guess whether they really want or need to cross it.
Cover photo by Tom Barrett on Unsplash
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