Obstacles Increase Flow

Wednesday, March 4th, 2015

Placing an obstacle in front of a crowded door slightly increases the flow rate and, more importantly, reduces the duration of clogs:

How to Make an Attractive City

Wednesday, January 28th, 2015

Alain de Botton explains how to make an attractive city:

  1. Not too chaotic, not too ordered.
  2. Visible life.
  3. Compact.
  4. Orientation and mystery.
  5. Scale.
  6. Make it local.

Collapsing Capitals

Friday, January 23rd, 2015

Ancient capital cities often grew for centuries, reached a Golden Age, and then collapsed rapidly:

Angkor was flourishing in the late 13th century when Zhou Daguan visited; a little over a century later, it was all but abandoned. Researchers are beginning to see similarities in how these ancient low-density cities failed — and this is of particular interest today because, even as our cities grow in extent and population, their densities are falling.


There had long been a debate about what led to the decline of Angkor and the southward move of the Khmer seat of power. Proposed explanations included the strain on theocratic rule of Hindu-Buddhist jostling; attacks by Thai armies; and changes brought about by maritime trade. But the Greater Angkor Project added a significant new possibility: extreme climate instability. Analysis of tree rings in neighbouring Vietnam showed long periods of droughts followed by periods of unusually wet monsoons in the 14th and 15th centuries.

The upheaval caused by flooding during mega-monsoons is clearly visible in remote sensing images produced by the project: erosion channels show rapidly moving water breaching a dam, crashing into the wall of a reservoir, then tearing away the edge of a residential area, flowing at a high level through housing, and later damaging a bridge. Perhaps the scenes in Angkor were not very different from those seen in recent years in New Orleans or Fukushima.

Sand accumulated in Angkor’s canals, and parts of the water network were cut off from each other. Damage to an old, complex water management system meant the city became less resilient in intervening periods of drought. Angkor, with its large population and broken infrastructure, would have found it hard to sustain itself.

The pattern of urbanism at Angkor was hardly unique: the Mayan cities that Pottier’s maps of Angkor reminded Fletcher of have long been recognised as low-density agrarian settlements. The lack of the wheel and the absence of draught animals meant that large quantities of food could not be transported, and cities had to be largely self-sufficient, growing maize, varieties of beans, squash, manioc and other staples of the region.

The city of Tikal, in present-day Guatemala, was one of the most important of these Mayan centres. In what is called its Late Classic Period, around 600 AD, there was a flowering of art and architecture: large plazas, palaces, pyramid temples, sculpture and painted ceramics (of the many structures still found in Tikal, a 65-metre high pyramid is one of the tallest man-made structures in all pre-Columbian America). Conservative estimates put the city’s population at around 45,000 during this period; the city extended over 160 square kilometres. Then, in the middle of the ninth century, Tikal collapsed.


Originally, the area of Tikal was around 70% upland tropical rainforest, and the rest swampy wetland. An extended family would build their houses in a cluster, with cultivable land attached. In all, the people of Tikal cleared around two-thirds of the rainforest to create their monuments and homes, and to fuel their fires. “In many ways they were managing the forest very effectively,” says Lentz. “But they weren’t aware that cutting down a forest reduces the amount of precipitation in the region. Then suddenly a horrible drought comes along, and they can’t figure out why they can’t supplicate their gods adequately to prevent it.”

It didn’t help that Tikal’s water management system had become increasingly reliant on collecting rainwater in reservoirs, at the cost of groundwater. “As Tikal grew and grew,” Lentz says, “they created all these pavements around the city, from which they’d divert water to the reservoirs. But this cut off the recharge capacity of the springs. When there was no longer any rainfall to fill up their reservoirs, the springs had dried up too.”

For centuries, the Maya at Tikal had been erecting stelae — upright stone slabs with hieroglyphs and depictions of gods and rulers. The last one is dated 869. Soon after, there are signs of what might today be called urban decay, with palaces being occupied by squatters. Charred, gnawed human bones from this late period suggest desperate times. Then, the city went quiet.


Lentz draws a comparison with a neighbouring city called El Zotz, which had a smaller population, which didn’t modify its landscape as drastically, and was thus able to survive the drought that felled Tikal.


Tikal, Angkor and Anuradhapura (which foundered in the 10th century after thriving for more than a millennium) were very different cities in their geography, environment and social and political functioning. But, Fletcher points out, they all had operational similarities: extensive land clearance, sprawling low-density settlement patterns, massive infrastructure — all of which are attributes of modern cities. The extended infrastructure of Angkor and Tikal proved vulnerable to a changing climate, something else that may be upon us.

Bushwick, Brooklyn 2015

Monday, January 19th, 2015

Bushwick, Brooklyn has changed over the years:

Ten Hours of Princess Leia Walking in NYC

Friday, November 14th, 2014

Ten Hours of Princess Leia Walking in NYC:

The Dancing Traffic Light

Monday, November 10th, 2014

People hate waiting to cross at the crosswalk, but what if you add a dancing traffic light?

In Gurgaon, India, Dynamism Meets Dysfunction

Saturday, November 8th, 2014

Gurgaon was widely regarded as an economic wasteland:

In 1979, the state of Haryana created Gurgaon by dividing a longstanding political district on the outskirts of New Delhi. One half would revolve around the city of Faridabad, which had an active municipal government, direct rail access to the capital, fertile farmland and a strong industrial base. The other half, Gurgaon, had rocky soil, no local government, no railway link and almost no industrial base.

As an economic competition, it seemed an unfair fight. And it has been: Gurgaon has won, easily. Faridabad has struggled to catch India’s modernization wave, while Gurgaon’s disadvantages turned out to be advantages, none more important, initially, than the absence of a districtwide government, which meant less red tape capable of choking development.


Ordinarily, such a wild building boom would have had to hew to a local government master plan. But Gurgaon did not yet have such a plan, nor did it yet have a districtwide municipal government. Instead, Gurgaon was mostly under state control. Developers built the infrastructure inside their projects, while a state agency, the Haryana Urban Development Authority, or HUDA, was supposed to build the infrastructure binding together the city.

And that is where the problems arose. HUDA and other state agencies could not keep up with the pace of construction. The absence of a local government had helped Gurgaon become a leader of India’s growth boom. But that absence had also created a dysfunctional city. No one was planning at a macro level; every developer pursued his own agenda as more islands sprouted and state agencies struggled to keep pace with growth.

The solution isn’t that complicated, as Alex Tabarrok points out:

If the rights to develop Gurgaon had originally been sold in very large packages, some five to seven proprietary but competitive cities could have been created in that region. Within this system the role of the state is to make it possible to auction large parcels of land. Once such parcels and associated rights to develop the land are created, private developers will provision public goods and services up to the edge of their property.

Cat Calls

Wednesday, October 29th, 2014

This video depicts a woman walking though New York City and receiving plenty of cat calls:

Naturally, there is no pattern at all to see here.

How To Make a Pile of Dough With the Traditional City

Thursday, October 9th, 2014

Nathan Lewis looks at how to make a pile of dough by bulldozing a big-box shopping center and replacing it with a dense urban neighborhood:

I took the example of a shopping center in Binghamton, New York. Binghamton is probably not a good place to do this, because nobody needs another nine million square feet of floorspace in Binghamton. However, since all shopping centers are basically the same, we can use that example. At a density of 100,000 people per square mile, reached in some Paris neighborhoods, 15,000 people or a third of the entire population of Binghamton could live here. However, those 15,000 people already have houses, so we don’t need to build any more in Binghamton. In a place like Darien, Connecticut, however (an upscale New York City suburb), lots of people might like to live in a place like this (good schools), and pay a premium for it, especially if it was within walking distance of the train station.

Binghamton Big Box

Bulldozing this thing is pretty easy, because its mostly just parking lots anyway, and the buildings themselves are rather insubstantial.

This photo is about 800 meters across, and the land plot is about 93 acres. That is quite large, actually.

Here are some of our design goals:

1) We are assuming that we have to interface with Suburban Hell as it exists, so that means lots of parking needs to be provided, and a way for automobiles to get in and out easily. Parking will be in enclosed, multistory parking garages, mostly integrated into multi-use buildings.

2) Our land use plan is something like this:

  • 60% building footprint
  • 30% parks, courtyards, yards, gardens, and other public and private open space, which consist of Places, not “green space”.
  • 10% roadways, broken down into:
  • About 20% of streets are Arterial Streets, with two to four lanes of dedicated automobile roadway in the middle, probably some trees or grass as a buffer, and sidewalks on either side. No on-street parking.
  • The remaining 80% of streets (by length) are Really Narrow pedestrian-centric streets, of 10-30 feet wide, no segregated automobile roadway, no sidewalks, and no green buffers.

3) Building height is generally 3-6 stories, a typical Traditional City height.

4) Some buildings can be taller, particularly those which are adjacent to Arterial Streets. This would be more of a Manhattan-style Hypertrophic approach. Big buildings and big streets go together easily. So, you can add your 35-story highrise apartments and offices here too, if you want.

5) The treatment of the perimeter is an interesting design point. How should our neighborhood interface with the rest of Suburban Hell? Put a wall around it? (Lots of walled cities are very nice.) Put a green buffer around it? It might be nice for it to be separated from the rest of Suburban Hell, like its own little island of Traditional City fabulousness. Shall we put a row of buildings along the existing very large automobile roadways? I opt here for a combination of some park space along some streets (isolation), and some buildings along other streets. One nice thing about park space is that you can decide to build on it later if you want. Ideally, although being long and skinny and serving as a buffer, this will be usable and enjoyable as a park, not just a wall of shrubbery.

6) Block size is roughly 100-200 feet along the short side and 200-500 feet along the long side.

So, here we go:

Big Box Proposal

The darkened areas are parks. The small darkened area on the left is a paved town square. You could add some smaller squares and parks here and there as well. The wide, double-lined streets are Arterial Streets. The single black lines are Really Narrow Streets.

Although most of the streets here are Really Narrow pedestrian streets, almost all of the blocks have at least one side adjacent to an Arterial Street. An entrance to enclosed parking can be put on the side facing the Arterial Street, so that cars can enter and exit without having to drive on the Really Narrow Streets. Vehicles will be allowed on the Really Narrow Streets, but, seeing as they would have to share the road with people walking, and also there’s no place to park there, the main reason that motorized vehicles would be on the smaller streets is for deliveries and dropoffs.

This site has about four million square feet. At 60% building footprint, and an average height of four stories, that would mean about 9.6 million square feet of space here. That is a lot, although some of it would be used for parking.

These Mesmerizing Maps of Where People Jog Reveal Something Telling About Major U.S. Cities

Sunday, October 5th, 2014

These mesmerizing maps of where people jog reveal something telling about major U.S. cities:

But as the Washington Post alleges, these aren’t just maps of the best places to go jogging. They’re also maps which clearly match up very closely with the neighborhoods of rich and poor people in those cities.

Runkeeper Washington DC

Note, for example, there aren’t many people using Runkeeper in London south of the Thames, or in Boston’s South Side, or anywhere in New York but the financial district, the richest parts of Brooklyn, and the Upper East Side (exception: some people do appear to be crossing through the South Bronx to use the bridges there). Scenic D.C. is rich with routes; southeastern D.C. less so. The farther you get away from rich coastal San Francisco, the less people are jogging. It goes on and on.

Runkeeper Atlanta

As “Know More” notes, the correlation isn’t unexpected: Richer people tend to prefer living near parks and rivers, which are also the best jogging spots. And the poor are less likely to spend their money on “rich people” things like expensive smartphones or fitness apps. (I’d also argue that fitness tracking of this manner tends to be a bourgeois affectation.) But what’s clear is that fitness and class status tend to be correlated.

Runkeeper Charlotte

A more in-depth article in The Atlantic argues that while the link between poverty and obesity is poorly understood, we can take away some major points.

Runkeeper Philadelphia

“… Poverty might make some people obese, but obesity definitely makes many people poorer, through two broad channels: (a) it reduces take-home pay, particularly for women; and (b) it’s related to health conditions that reduce discretionary income, too.” Black women in particular are victims of this trend.”

Clearly the best explanation is that the poor are less likely to spend their money on “rich people” things like expensive smartphones or fitness apps.

Los Angeles Isn’t London

Wednesday, October 1st, 2014

Los Angeles isn’t London, Dave Munson notes, but contemporary California housing is built for an English climate, rather than a Mediterranean one:

Traditional Mediterranean and Arab cultures both used courtyard houses. Exterior walls in these cultures were often plain or even drab, with much more of the focus being on the interior courtyard. By having a smaller landscaped area and using native plants rather than ones introduced from a wetter climate, a household could cut its water use dramatically. The courtyard house also takes advantage of microclimates, shared walls, shading, and the solar chimney effect to naturally ventilate the house and use less energy than the detached home.

Contemporary California House vs. Mediterreanean

Tree Cathedral

Sunday, September 14th, 2014

Giuliano Mauri conceived a Tree Cathedral, which was started near the northern Italian city of Bergamo in 2010, a year after his death:

The Tree Cathedral consists of 42 columns forming a basilica of five aisles. Fir poles and branches from hazels and chestnuts have been woven together to create a supporting structure for the 42 beeches planted to eventually grow and form the columns. As planned, the surrounding support structure will deteriorate as the beeches grow, creating a seamless transition from the man-made to the natural.

Tree Cathedral or Cattedrale Vegetale near Bergamo by Giuliano Mauri

Standing at the foot of Mount Arera, the Tree Cathedral’s structure includes 1,800 fir poles, 600 chestnut branches, and 6,000 meters of hazel branches joined together with wood, nails, and string. The Cathedral takes up 650 square meters and took months to construct. It is more than 90 feet long, nearly 80 feet wide, and ranges in height from about 16 feet to nearly 70 feet.

I can easily imagine Tolkien’s elves building this way — which brings us to Eric S. Raymond’s thoughts on Tolkien and Christopher Alexander’s Timeless Way of Building:

Before you read the rest of this post, go look at these pictures of a Hobbit Pub and a Hobbit House. And recall the lovely Bag End sets from Peter Jackson’s LOTR movies.

Hobbit Pub

I have a very powerful reaction to these buildings that, I believe, has nothing to do with having been a Tolkien fan for most of my life. In fact, some of the most Tolkien-specific details — the round doors, the dragon motifs in the pub — could be removed without attenuating that reaction a bit.

Hobbit House in Chester County, PA

To me, they feel right. They feel like home. And I’m not entirely sure why, because I’ve never lived in such antique architecture. But I think it may have something to do with Christopher Alexander’s “Timeless Way of Building”.

How To Grow a City in Honduras

Friday, August 29th, 2014

Reason looks at how to grow a city in Honduras:

Some People Don’t Lock Their Doors

Thursday, August 28th, 2014

As hard as it is to believe, some people don’t lock their doors — even in New York City:

A 2008 survey by State Farm Insurance of 1,000 homes across the country reported that fewer than half of those surveyed always locked their front doors. And while people who habitually lock their doors are incredulous that others do not, those who don’t lock are surprised that anyone would be shocked by it.


According to the F.B.I.’s most recent annual Uniform Crime Report, of the estimated 2,222,196 burglaries committed nationwide in 2008, 32.2 percent were unlawful entries without force. And a spokesman for the New York City Police Department reported that of the 19,263 burglaries that took place in New York City in 2009, 5,041 did not involve forced entry.

These figures include commercial as well as residential properties, and burglaries without forced entry cannot be flatly equated with those that involve unlocked doors, because they may involve open windows; unauthorized use of a key; or theft by workers, family members or business associates. But unlocked doors are certainly a factor.

Inspector James Murtagh is the commanding officer of the 19th Precinct on the Upper East Side of Manhattan, which includes Park Avenue doorman buildings, brownstones and apartment houses. In his precinct, he estimates that 25 percent of burglaries are a result of an open door or window.

While out-of-towners may cling to the notion of New York as a city of triple locks and metal bars bracing the door — an image common in movies from the 1960s and 1970s — that idea is dramatically out of date. According to the Police Department, there were 210,703 burglaries in the city in 1980, more than 10 times as many as there were last year.

And in some ways, Inspector Murtagh says, the city may be a victim of its own success — people may have become too comfortable.

Slum-Free Hanoi

Wednesday, August 20th, 2014

Across the developing world, people move from the country to the outskirts of the city, where they build slums:

Their homes are built illegally, so there is no state provision of services — no electricity, running water, waste or sewerage provision. And shack by shack, the slum is born.

Hanoi has faced the same population pressures as other Asian cities. But thanks to vague and informal conventions, the state has been able to avoid extreme levels of disservice, even to the most impoverished new urban areas. And the construction of homes themselves has remained at least loosely connected to the regulations of the more formal suburbs. Together these factors have prevented the formation of slums as they are typically defined. But how has this come about?

By some estimates, 90% of the buildings in Hanoi have been built without official permission — the land untitled and never surveyed — the effects evident from even a cursory view of the city. Skinny buildings abut each other on narrow plots of land, and from the motorbike-choked thoroughfares, narrow alleys splinter off into neighbourhoods. The unplanned developments have been carried out by the quasi-legal construction industry.


Under socialist decree, all citizens were entitled to homes. Private property and construction was heavily restricted. Instead, housing was provided in state-run Soviet-style collective flats. But as growth increased, the new government struggled to maintain existing facilities and keep pace with demand. Occupants began building their own additions, often circumventing the arduous permit process. Other residents built illegally on public land.

Caught in a bind, having forbidden private construction but unable to house everyone, the government caved in and allowed private construction but with minimum standards. “Effectively, anyone could build a house on a minimum plot of about 20 square metres,” says Michael DiGregorio of the Asia Foundation. But oversight was limited, and a culture of partially and completely illegal construction began to flourish.

As the 1990s progressed, increased wealth fuelled demand, and illegal construction grew sharply. In 1995, there were about 1,000 illegal projects in the city — and those were just the reported cases. The city also began to spread out, progressively consuming villages and rice paddies to keep pace with demand for homes. Urban planners call this “spontaneous urban development”. Most of the world calls it “slums”. But in Hanoi, with the unusual mixture of basic regulation and control, a strange thing happened. “The negative side of this development was substandard infrastructure,” says DiGregorio, “but there was also a positive.” That positive came from the enlightened regulatory attitude of authorities.

In the culture of semi-legal construction, if someone built a structure that adhered to minimum standards, it became legal — and for the most part was provided with basic services such as electricity and sanitation. In most developing cities, those flooding from the countryside end up living in sprawling squatter encampments, lacking basic sanitation and vulnerable to eviction. But in Hanoi, the new arrivals could build houses that didn’t have official permission but often received basic services anyway. Because the buildings were legal, residents had incentive to improve and rebuild with stronger materials when their finances allowed. As well as these new homes, there was a similarly positive trend in the existing overcrowded and under-serviced public housing blocks, with an incentive for residents to improve the buildings.