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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
The traditional narrative when it comes to NIMBYs is that these are individuals acting out of self-interest. Quintessentially, these are people who own their home and do not want development "in their backyard" out of fear that it might negatively impact the value of their property and/or have a negative impact on their local community.
But in reality, anti-development sentiment is likely more nuanced than this. In a recent working paper called "The Symbolic Politics of Housing," researchers at UC, Berkeley and UC, Davis show that anti-development sentiment is not always just about self-interest; rather, it can be predicted by how people feel about certain "salient symbols."
This is based on something called "symbolic politics theory" and it works like this: We all have positive and negative associations with certain "symbols." Often these are developed early in life. And so how we might feel about a development or a particular land use policy, depends on the symbols attached to it and whether we like them.
Here's an example.
Consider two identical apartment developments happening in your neighborhood. The first is being developed by faceless "Wall Street investors" and the second is being developed by a nice local entrepreneur who also happens to be of the exact same ethno-cultural group as you.
If you don't like people on Wall Street and you don't want them profiting from the development, the research suggests that you are more likely to oppose the first development, even though it's the same as the second one, and maybe even if it runs counter, in some way, to your own self-interest. You just don't like the symbol attached to it.
This is also why people who live in cities tend to be more pro-development on average. It reinforces symbols that they already like; ones associated with cities, density, and urban living. This is fascinating, but it also complicates matters. Because it means that strong opinions are not just being formed based on measurable impacts. It's also a question of symbols and feelings.
We have spoken a lot about pedestrian fatalities over the years (here, here, and here are a few posts), and, if there is a general rule of thumb, it is that pedestrians are safer in dense urban environments where there are a lot of other people walking around.
But another important factor might be average vehicle size. Here is a recent study by Justin Tyndall that combined US pedestrian crash data with car sizes to come up with the effect of front-end vehicle height on pedestrian death probability. This is an important metric because larger/higher front-ends are more likely to fatally hit someone in their chest and/or head.
What was ultimately found was that a 10 cm increase in front-end height -- which is really not a lot -- causes a 22% increase in pedestrian fatality risk! Meaning that something as simple as reducing front-end heights could reduce pedestrian fatalities. By his estimation, a 1.25 m height cap would reduce US pedestrian deaths by about 509 people each year.
This is pretty interesting, especially considering that average car sizes seem to keep going up.
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