The five technologies that changed the way we build cities

Without electricity, steel and lifts, there'd have been no Chrysler Building. Image: Getty.

Like most people who live in London, I spend an inordinate amount of time thinking about, or travelling on, public transport. And when walking around, I find myself constantly on the hunt for the shortest possible route from A and B. We city-dwellers tend to be a pretty impatient lot, and that can make us a bit blind to the details that surround us.

But I think it’s about time that we started to take notice of how the city works.

I’ve explored this very topic in my new book, Science and the City. It takes in cities on six continents, and looks at the technologies they’re using to change the urban landscape – as well as those developments from the lab that might utterly transform them in future.

Here is my own personal Top 5 – the five specific developments that, I believe, created the modern city.

1) Steel

Until the mid-1800s, large buildings were constructed from stone, brick and iron. All of these were strong but heavy, which limited how tall a structure could be before it began to collapse under its own weight.
To make taller buildings then, engineers needed a new material. So, they added small quantities (between 0.02 and 2 per cent) of carbon to iron, along with other impurities, to make an alloy. The steels produced were lightweight and easy to shape, while being hard and strong enough to form walls and foundations – perfect for use in tall buildings.

The alloys that were first developed in the early steel age gave birth to the railways, bridges, aircraft, cars, reinforced concrete, and, of course, the skyscrapers that now dominate our cities. For me, it's the king of urban materials.

2) Toilets

 

Ok, I’m cheating a bit here, because when I say toilets, I’m also referring to the sewers they empty into. Let’s start with this delightful thought. London’s sewers manage approximately 1.25bn kilograms of poo each year.
Before Joseph Bazalgette built his extensive sewer network, much of the city’s waste was discharged directly into the Thames. In Chicago, too, the uncontrolled mixing of water and waste led the city to take drastic action – they reversed the flow of their river, using a series of canals and locks.

It was the widespread adoption of plumbed toilets that first properly separated people from their waste, making the streets and waterways of the urban landscape considerably less smelly and more hygienic. It also kick-started the large-scale approach to water treatment that we all rely on today.

3) Electrification

A city’s electricity might be generated in any number of ways – from the burning of fossil fuels, through to wind energy from turbines. But electricity ultimately changed the world because it provided a way to rapidly and safely "pipe" energy to homes and businesses.

It was Thomas Edison who built the world’s first integrated power plant and grid system, and Nikola Tesla who figured out the best way to distribute the electricity it generated. Thanks to the resulting network, cities got electric streetlamps and escalators, trams, metros and trains, as well as homes full of labour-saving gadgets. Electricity also provided a way for city-dwellers to communicate over long distances – first, via the telegraph, later the radio, and now via cabled and wireless internet. Energy storage, however, remains a challenge facing every city.

4) Cars

While many of us try to avoid driving in the city, lots of the things we associate with urban life – traffic lights, road markings, signs and crossings – were all introduced to cities precisely because cars were on the road. 

The first motor vehicles had to be preceded by a person on foot, waving a red flag, but the invention of traffic lights changed all that. They also introduced structure to road networks, and gave pedestrians a place to cross. Road signage too is designed with a vehicle in mind: its retroreflective surface is designed specifically to be seen with headlights. 

If we get to a stage where the only cars on the road are driverless, our familiar street furniture could disappear entirely. Who needs a big shiny sign when a car could communicate with a sensor buried in the road?

5) Lifts

This one might seem a little controversial, but hear me out. Before the invention of the humble lift, living several storeys up was a pain. After them, tall buildings became practical, and top-floor apartments began to represent the ultimate in desirable city-living. 


In the centre of cities, where land has always been priced at a premium, going "up" rather than "out" became the norm, so skyscrapers started popping up everywhere. Lifts didn’t just change the way we did things – they built the city, and no-one could have predicted that outcome.

Lifts, and the skylines they created, may well have had a secondary impact too. A number of recent studies (such as this, or this) have suggested that densely-packed cities produce lower emissions, and are more energy-efficient, than those that have grown by low-rise sprawl.

The thing is, cities have never been as big, or as busy, as they are now. And while these five developments have given us a good foundation to work with, as our cities grow, we’ll need to find much better ways to power, clean, build, travel through and live in them. And for that, we’ll have to look to great science and clever engineering yet again.

What other technologies would you add to the list? Tweet me @laurie_winkless or using the hashtag #cityscience.

Laurie Winkless is a science writer based in London. Her book, Science and the City: The Mechanics behind the Metropolis will be published by Bloomsbury Sigma on 11 August.

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Urgently needed: Timely, more detailed standardized data on US evictions

Graffiti asking for rent forgiveness is seen on a wall on La Brea Ave amid the Covid-19 pandemic in Los Angeles, California. (Valerie Macon/AFP via Getty Images)

Last week the Eviction Lab, a team of eviction and housing policy researchers at Princeton University, released a new dashboard that provides timely, city-level US eviction data for use in monitoring eviction spikes and other trends as Covid restrictions ease. 

In 2018, Eviction Lab released the first national database of evictions in the US. The nationwide data are granular, going down to the level of a few city blocks in some places, but lagged by several years, so their use is more geared toward understanding the scope of the problem across the US, rather than making timely decisions to help city residents now. 

Eviction Lab’s new Eviction Tracking System, however, provides weekly updates on evictions by city and compares them to baseline data from past years. The researchers hope that the timeliness of this new data will allow for quicker action in the event that the US begins to see a wave of evictions once Covid eviction moratoriums are phased out.

But, due to a lack of standardization in eviction filings across the US, the Eviction Tracking System is currently available for only 11 cities, leaving many more places facing a high risk of eviction spikes out of the loop.

Each city included in the Eviction Tracking System shows rolling weekly and monthly eviction filing counts. A percent change is calculated by comparing current eviction filings to baseline eviction filings for a quick look at whether a city might be experiencing an uptick.

Timely US eviction data for a handful of cities is now available from the Eviction Lab. (Courtesy Eviction Lab)

The tracking system also provides a more detailed report on each city’s Covid eviction moratorium efforts and more granular geographic and demographic information on the city’s evictions.

Click to the above image to see a city-level eviction map, in this case for Pittsburgh. (Courtesy Eviction Lab)

As part of their Covid Resource, the Eviction Lab together with Columbia Law School professor Emily Benfer also compiled a scorecard for each US state that ranks Covid-related tenant protection measures. A total of 15 of the 50 US states plus Washington DC received a score of zero because those states provided little if any protections.

CityMetric talked with Peter Hepburn, an assistant professor at Rutgers who just finished a two-year postdoc at the Eviction Lab, and Jeff Reichman, principal at the data science research firm January Advisors, about the struggles involved in collecting and analysing eviction data across the US.

Perhaps the most notable hurdle both researchers addressed is that there’s no standardized reporting of evictions across jurisdictions. Most evictions are reported to county-level governments, however what “reporting” means differs among and even within each county. 

In Texas, evictions go through the Justice of the Peace Courts. In Virginia they’re processed by General District Courts. Judges in Milwaukee are sealing more eviction case documents that come through their courtroom. In Austin, Pittsburgh and Richmond, eviction addresses aren’t available online but ZIP codes are. In Denver you have to pay about $7 to access a single eviction filing. In Alabama*, it’s $10 per eviction filing. 

Once the filings are acquired, the next barrier is normalizing them. While some jurisdictions share reporting systems, many have different fields and formats. Some are digital, but many are images of text or handwritten documents that require optical character recognition programs and natural language processors in order to translate them into data. That, or the filings would have to be processed by hand. 

“There's not enough interns in the world to do that work,” says Hepburn.


Aggregating data from all of these sources and normalizing them requires knowledge of the nuances in each jurisdiction. “It would be nice if, for every region, we were looking for the exact same things,” says Reichman. “Instead, depending on the vendor that they use, and depending on how the data is made available, it's a puzzle for each one.”

In December of 2019, US Senators Michael Bennet of Colorado and Rob Portman of Ohio introduced a bill that would set up state and local grants aimed at reducing low-income evictions. Included in the bill is a measure to enhance data collection. Hepburn is hopeful that the bill could one day mean an easier job for those trying to analyse eviction data.

That said, Hepburn and Reichman caution against the public release of granular eviction data. 

“In a lot of cases, what this gets used for is for tenant screening services,” says Hepburn. “There are companies that go and collect these data and make them available to landlords to try to check and see if their potential tenants have been previously evicted, or even just filed against for eviction, without any sort of judgement.”

According to research by Eviction Lab principal Matthew Desmond and Tracey Shollenberger, who is now vice president of science at Harvard’s Center for Policing Equity, residents who have been evicted or even just filed against for eviction often have a much harder time finding equal-quality housing in the future. That coupled with evidence that evictions affect minority populations at disproportionate rates can lead to widening racial and economic gaps in neighborhoods.

While opening up raw data on evictions to the public would not be the best option, making timely, granular data available to researchers and government officials can improve the system’s ability to respond to potential eviction crises.

Data on current and historical evictions can help city officials spot trends in who is getting evicted and who is doing the evicting. It can help inform new housing policy and reform old housing policies that may put more vulnerable citizens at undue risk.

Hepburn says that the Eviction Lab is currently working, in part with the ACLU, on research that shows the extent to which Black renters are disproportionately affected by the eviction crisis.

More broadly, says Hepburn, better data can help provide some oversight for a system which is largely unregulated.

“It's the Wild West, right? There's no right to representation. Defendants have no right to counsel. They're on their own here,” says Hepburn. “I mean, this is people losing their homes, and they're being processed in bulk very quickly by the system that has very little oversight, and that we know very little about.”

A 2018 report by the Philadelphia Mayor’s Taskforce on Eviction Prevention and Response found that of Philadelphia’s 22,500 eviction cases in 2016, tenants had legal representation in only 9% of them.

Included in Hepburn’s eviction data wishlist is an additional ask, something that is rarely included in any of the filings that the Eviction Lab and January Advisors have been poring over for years. He wants to know the relationship between money owed and monthly rent.

“At the individual level, if you were found to owe $1,500, was that on an apartment that's $1,500 a month? Or was it an apartment that's $500 a month? Because that makes a big difference in the story you're telling about the nature of the crisis, right? If you're letting somebody get three months behind that's different than evicting them immediately once they fall behind,” Hepburn says.

Now that the Eviction Tracking System has been out for a week, Hepburn says one of the next steps is to start reaching out to state and local governments to see if they can garner interest in the project. While he’s not ready to name any names just yet, he says that they’re already involved in talks with some interested parties.

*Correction: This story initially misidentified a jurisdiction that charges $10 to access an eviction filing. It is the state of Alabama, not the city of Atlanta. Also, at the time of publication, Peter Hepburn was an assistant professor at Rutgers, not an associate professor.

Alexandra Kanik is a data reporter at CityMetric.