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Urban Development

What can satellite imagery tell us about secondary cities? (Part 2/2)

Sarah Elizabeth Antos's picture
In the previous blog, we discussed how remote sensing techniques could be used to map and inform policymaking in secondary cities, with a practical application in 10 Central American cities. In this post, we dive deeper into the caveats and considerations when replicating these data and methods in their cities.

Can we rely only on satellite? How accurate are these results?

It is standard practice in classification studies (particularly academic ones) to assess accuracy from behind a computer. Analysts traditionally pick a random selection of points and visually inspect the classified output with the raw imagery. However, these maps are meant to be left in the hands of local governments, and not published in academic journals.

So, it’s important to learn how well the resulting maps reflect the reality on the ground.

Having used the algorithm to classify land cover in 10 secondary cities in Central America, we were determined to learn if the buildings identified by the algorithm were in fact ‘industrial’ or ‘residential’. So the team packed their bags for San Isidro, Costa Rica and Santa Ana, El Salvador.

Upon arrival, each city was divided up into 100x100 meter blocks. Focusing primarily on the built-up environment, roughly 50 of those blocks were picked for validation. The image below shows the city of San Isidro with a 2km buffer circling around its central business district. The black boxes represent the validation sites the team visited.
 
Land Cover validation: A sample of 100m blocks that were picked to visit in San Isidro, Costa Rica. At each site, the semi-automated land cover classification map was compared to what the team observed on the ground using laptops and the Waypoint mobile app (available for Android and iOS).

What can satellite imagery tell us about secondary cities? (Part 1/2)

Sarah Elizabeth Antos's picture

The buzz around satellite imagery over the past few years has grown increasingly loud. Google Earth, drones, and microsatellites have grabbed headlines and slashed price tags. Urban planners are increasingly turning to remotely sensed data to better understand their city.

But just because we now have access to a wealth of high resolution images of a city does not mean we suddenly have insight into how that city functions.

The question remains: How can we efficiently transform big data into valuable products that help urban planners?

In an effort a few years ago to map slums, the World Bank adopted an algorithm to create land cover classification layers in large African cities using very high resolution imagery (50cm). Building on the results and lessons learned, the team saw an opportunity in applying these methods to secondary cities in Latin America & the Caribbean (LAC), where data availability challenges were deep and urbanization pressures large. Several Latin American countries including Argentina, Bolivia, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama were faced with questions about the internal structure of secondary cities and had no data on hand to answer such questions.

A limited budget and a tight timeline pushed the team to assess the possibility of using lower resolution images compared to those that had been used for large African cities. Hence, the team embarked in the project to better understand the spatial layout of secondary cities by purchasing 1.5 meter SPOT6/7 imagery and using a semi-automated classification approach to determine what types of land cover could be successfully detected.

Originally developed by Graesser et al 2012 this approach trains (open source) algorithm to leverage both the spectral and texture elements of an image to identify such things as industrial parks, tightly packed small rooftops, vegetation, bare soil etc.

What do the maps look like? The figure below shows the results of a classification in Chinandega, Nicaragua. On the left hand side is the raw imagery and the resulting land cover map (i.e. classified layer) on the right. The land highlighted by purple shows the commercial and industrial buildings, while neighborhoods composed of smaller, possibly lower quality houses are shown in red, and neighborhoods with slightly larger more organized houses have been colored yellow. Lastly, vegetation is shown as green; bare soil, beige; and roads, gray.

Want to explore our maps? Download our data here. Click here for an interactive land cover map of La Ceiba.

获奖摄影作品捕捉可持续发展城市的未来

Xueman Wang's picture
Also available in: English

可持续城市摄影作品竞赛的出发点很简单。我们想要了解世界各地的人们听到“可持续城市”这个词会“看”到什么。

   

可持续城市全球平台从全球四十多个国收到就九十多张参赛作品,内容发人深省。

摄影师通过照片试图传递的是一种需求:对能使城市恢复能力更强、更加可持续的基础设施的迫切需求,或者追求为所有人建设可持续社区的绿色理想的需求。

今天是世界城市日,是最适合与你们分享本次摄影竞赛十位入围者名单的日子, 这些入围者中包括三位获奖者和一位气候行动荣誉奖获得者。
 
人们几乎可以从Yannick Folly的获奖作品中感受到贝宁城市的混乱和汽车尾气的味道,汽车沿着狭窄的巷子艰难爬行,与摩托车和行人挤在一起。

 

Yanick Folly (贝宁) 获奖者

日复一日的发展,我们的世界一直在变化。看看充满活力的贝宁集市就能感受到这种变化。#SustainableCities

这张照片提醒人们城市是由人组成的。任何建设可持续城市的解决方案对城市居民而言必须是合理的,因为每天行走在城市街道上的人是他们每天。

 

这种渴望在其他作品中也显而易见。

 

尽管很多摄影师来自世界各地的发展中国家,然而,其中相当一部分分享的却是在我们看来的环境友好型城市:新加坡、阿姆斯特丹、伦敦、巴黎等的照片。我们看到了很多发达国家公园的照片,都在传递同一个信息: 这样的绿色空间和人行道正是我们希望城市拥有的。

 

Adedapo Adesemowo(英国/尼日利亚)

现在的奥林匹克公园曾经是石油、沥青、砷和铅的废物倾倒场所 #SustainableCities
很多作品也反映了人们梦寐以求的城市和大部分人实际生活在其中的城市的巨大差别。
 
我们收到了很多可能被许多人归类为“农村地区”的照片,但是我们应该抛开这些偏见:一些发展中国家的“城市”不过是简陋的城镇而已。
 
所以当我们看到来自尼日利亚的Oyewolo Eyitayo的这幅获奖作品时,就更有理由感到兴奋。在你看到一半是土路的路上成排的太阳能板之前,你可能觉得这只是一张典型的平淡无奇的城市郊区的照片。
 
Oyelowo Eyitayo (尼日利亚) – 获奖者
选择太阳能是简单而有效的#气候行动,可以帮助抵御气候变化。#SustainableCities

改造城市滨水区

Fen Wei's picture
Also available in: English
HafenCity, Hamburg. Photo Credit: ELBE&FLUT / Thomas Hampel at http://www.hafencity.com
港口新城,汉堡。
图片来源: ELBE&FLUT / Thomas Hampel at http://www.hafencity.com
 “滨水区不只是孤立存在的。它与其他所有的东西相关。” —— 杰出的城市规划师Jane Jacobs说。
 
这种关系是两方面的;它指的是城市与其滨水区的关系,这种关系不断变化正如城市本身不断变化一样。
 
在工业化时代,城市滨水区是服务于城市的后院,但最近几十年来,它已经从以前的定义发展演化,有了新的含义。

一方面,在改变城市结构甚或重塑城市形象方面,滨水区发挥了更重要的作用。
 
另一方面,成功的城市滨水区也展示了可以怎样释放和利用城市资源(如可利用的土地、更清洁的水、历史遗产保护和城市更新),以及怎样将这些因素融入城市和公众的生活。

[参阅: 城市土地再生:利用私人投资从业者指南]

Pipeline to Work: Including persons with disabilities in skills development and employment projects

Charlotte McClain-Nhlapo's picture
Photo: Dane Macri/The Advocacy Project via Flickr CC
Photo: Dane Macri/The Advocacy Project via Flickr CC.

The relationship between poverty and disability goes both ways: disability increases the risk of poverty, and the conditions of poverty increase the risk of disability.

Yet, little attention has been given to the employment readiness of persons with disabilities. This is of concern given that the employment rates of persons with disabilities are a third to half of the rates for persons without disabilities, with unemployment rates as high as 80%-90% in some countries.

[Learn more: Disability Inclusion]

Disability is a complex, evolving, and multidimensional concept. Currently, it is estimated that 15% of the world population experiences some form of disability, with prevalence rates higher in developing countries. As opportunities for sustainable income generation are directly tied to a person’s access to finance, markets, and networks, persons with disabilities usually face significant challenges in accessing these, due to:

  • non-inclusive regulations and policy,
  • lack of resource allocation,
  • stigma and societal prejudice,
  • low educational participation, and
  • inability to access their own communities and city spaces.
To continue building inclusive cities, research tells us that countries cannot achieve optimal growth by leaving behind a large group of their citizens – persons with disabilities – with economic losses from employment exclusion ranging from 3 to 7 % of the GDP. We also know that when you combine gender and disability, the challenges facing women with disabilities compound. Women with disabilities are more likely to earn less than men with disabilities and they are affected by inaccessible sanitation, smaller social and professional networks, and gender-based violence – see, for example, labor force data from the UK.

We need to do much more to ensure that women with disabilities are mainstreamed into projects that seek to empower women as entrepreneurs and change agents.

Expanding equitable opportunities for persons with disabilities is at the core of the World Bank’s work to build sustainable and inclusive communities. So, what might a disability-responsive moonshot look like for development projects addressing work for persons with disabilities? Here’s what we’re doing at the World Bank:

These winning photos capture the future of sustainable cities

Xueman Wang's picture
Also available in: 中文
The premise behind the Sustainable Cities photo competition was simple. We wanted to learn what people around the world “see” when they hear the words “sustainable cities.”
 
The submissions – and we at the Global Platform for Sustainable Cities received more than 90 entries from over 40 countries around the world – are very revealing.

What the photographers tried to communicate was a need: both the urgent need for infrastructure that leads to more resilient, sustainable cities, or a need to aspire to greener ideals of building sustainable communities for all.

There is no better day than today, World Cities Day, for us to share with you the 10 finalists – including 3 winners and an honorable mention for climate action – of the photo competition.

In the winning photo by Yanick Folly, one can practically feel the chaos of a city in Benin, the smell of exhaust fumes as cars crawl up alongside motorcycles and pedestrians down narrow alleyways.

Yanick Folly (Benin) – Winner
Growing day by day, our world is always moving. Just see the big vibrant Benin market. #SustainableCities

The photo is also a reminder that cities are made of people. Any set of solutions for “sustainable cities” will have to make sense to a city’s inhabitants, who tread its streets daily.
 
In other photos, the aspiration is palpable. 

Many of the photographers are nationals of developing countries from all over the world. Yet quite a few of them shared photos of cities we regard as environmentally friendly: Singapore, Amsterdam, London, and Paris... We saw many photos of parks in developed countries, and heard the same message: These green spaces and pedestrian walkways are what we want in a city.
 
Adedapo Adesemowo (UK / Nigeria)

From a waste dumping ground for oil, tar, arsenic, and lead to an Olympic park. #SustainableCities
Many photos also reflect the vast difference between the aspirational city, and what most people actually live with.
 
We received photos of what many of us may categorize as rural areas, but we should reconsider these preconceptions: some “cities” in developing countries are little more than makeshift towns.
 
So, it is all the more reason why we are excited about this winning photo by Oyewolo Eyitayo from Nigeria. You might think this is an uneventful photograph of a typical urban suburb. Except that the half dirt roads are lined with solar panels.
 
Oyelowo Eyitayo (Nigeria) – Winner
Going solar is a simple & impactful #climateaction that can help combat climate change. #SustainableCities

Five lessons on affordable housing provision from Indonesia

Dao Harrison's picture
When first-time homeowner Dewi moved into her new house in the Yogyakarta area a year ago, thanks to a government subsidy program, she thought: everything is perfect.
 
Well, not quite. Located an hour away from the city center, Dewi’s house is far from employment opportunities, shopping, and schooling for her two children. Two years after completion, more than half the housing development remains unoccupied. Because the house is not connected to the local water system, Dewi buys water twice a week. When seasonal floods are underway, the heavy rains impede access to her house.



Providing affordable and adequate housing has become a top policy priority for the government of Indonesia with the launch of Satu Juta Rumah (One Million Homes) program. Previous efforts to address the demand for affordable housing – a function of both new annual demand creation and an unmet housing deficit – had not effectively improved housing outcomes at the scale necessary.
Source:  Ministry of Public Works and Housing, Indonesia

But should homeownership volume be the sole indicator of a successful housing subsidy program? Is it possible to have a program that meets the government’s needs to be fiscally and economically cost effective, while also responding to the private market as well as the needs of residents?
 
Options are being explored. The recently approved National Affordable Housing Program Project (NAHP), for example, aims to innovate the affordable housing market by addressing bottlenecks and actively engaging the private sector in delivering for unserved segments. So far, Indonesia’s efforts provide valuable lessons. The lessons are:

“Better Planning, Better Cities” – Cities to share smart solutions to urban sustainability

Xueman Wang's picture
Lois Goh / World Bank

There is strength in numbers, the old idiom goes. Indeed, history shows that collaboration fosters ideas and results. Next week, the Global Platform for Sustainable Cities, or GPSC, will convene in New Delhi, India, to again share ideas and build on their collective vision: to work towards shaping cities that are sustainable, thriving, and inclusive through the decades ahead.
 
The gathering starting on October 30 is only the GPSC’s second annual meeting, as we launched the platform just last year in Singapore. Yet the 27 participating cities across 11 countries—and more members are very welcome—are moving ahead with confidence, embarking on innovative programs to realize their vision and galvanizing their national governments to establish platforms of their own. China, Malaysia, and India in Asia, Paraguay and Brazil in Latin America, and other participating cities are actively pursuing sustainable urbanization.
 
This strength in numbers is made possible by staunch supporters. The Global Environment Facility (GEF) is integral to the progress of the GPSC, and numerous partners such as UN agencies, development banks, and civil society organizations contribute to its success—amongst them the World Resources Institute, ICLEI (Local Governments for Sustainability), and the C40 Cities Climate Leadership group (C40).
 
What are the aims of the GPSC? Forging a shared vision for urban sustainability is its overarching goal, and this achievement would not be possible without connecting cities. 
 

In more concrete terms, the GPSC aims to be a global knowledge repository on integrated urban planning – both best practices and lessons learned. The newly launched GPSC website, www.thegpsc.org, hosts a collection of datasets, indicators, and analyses on trends in urbanization. This library of information assists cities in identifying the gaps in urban infrastructure and the provision of basic services. The data collected will improve the cities’ capacity to monitor and report the status of their “sustainability,” and to better formulate and implement strategies.
 
The GPSC’s 2nd annual meeting is organized around the theme of “Better Planning, Better Cities - Smart Solutions to Urban Sustainability,” and this second meeting will focus on using a data-driven approach for planning action. The many scheduled events will follow this approach, including the Mayor’s Roundtable, high-level panel discussions, and in-depth learning events. 

Understanding transit-oriented development through bike-sharing big data

Wanli Fang's picture
Also available in: 中文
As one of over 20 million people who work and live in Beijing, China, I used to find commuting to work in rush-hour traffic rather painful. However, things have changed dramatically since last year. Now I can bypass the traffic by riding a shared bike to the closest metro station and make better use of public transit. Similar change is happening to my family and friends.

The unprecedented booming of dockless shared bikes in China presents a promising solution to the “last-mile problem” that has perplexed city planners for years: providing easier access to the mass transit system while ensuring good ridership. Thanks to the GPS tracking device installed on thousands of dockless shared bikes, city planners in China are now equipped with new and better information to analyze the demand for—and the performance of—public transit systems. For the first time, city managers can clearly map out the attractiveness and accessibility of metro stations by analyzing individual-level biking trips.

This innovation is good news to efforts to build more livable, sustainable cities through transit-oriented development (TOD). For example, to support the recently launched GEF Sustainable Cities Integrated Approach Pilot Project, we have been working with Mobike, a major bike-sharing company, to conduct an analysis utilizing the data of biking trips around metro stations in our project cities. Below are a few interesting observations:
  • Revisiting the scope of TOD. A commonly accepted textbook definition of the core area of TOD is an 800-meter radius around the metro station or other types of public transit hubs. This definition is based on the distance that can be reached by a 10-minute walk. However, the actual catchment of a metro station can reach a 2-3 km radius when biking prevails, as in Demark and Netherland. Our analysis illustrates that a big chunk of biking trips around metro stations even go beyond the 3km radius (see bright blue traces in Figure 1 below). This indicates that the spatial scope of planning and design around the metro stations should be contextualized. Accordingly, the price premium associated with adjacency to public transit service is more likely to be shared by a broader range of nearby real estate properties than expected.
Figure 1: Biking traces around major metro station in Beijing (left) and Shenzhen (right).

[Read: TOD with Chinese characteristics: localization as the rule rather than the exception] –  which also discusses defining the scope of TOD. 

透过共享单车大数据了解公共交通导向的开发(TOD)

Wanli Fang's picture
Also available in: English
作为在北京工作和生活的两千多万人中的一员,我曾经常为高峰时段上下班发愁。不过从去年开始情况发生了变化。现在我可以骑着共享单车避开拥堵,到最近的地铁站搭乘地铁,更充分享受地公共交通服务的便利。我的亲朋好友也有类似的经历。
 
无桩共享单车在中国前所未有的蓬勃发展,为多年来困扰城市规划者们的“最后一公里问题”提供了颇有希望的解决方案:既让公共交通系统更便于使用,又能保证良好的客流量。许多无桩共享单车安装了GPS跟踪设备,为城市规划者分析公共交通系统的需求和绩效提供了更精准的新的数据来源。通过分析个人骑行数据,城市管理者第一次可以清楚地了解各个地铁站的吸引力和可达性。
 
这项技术创新对于通过公共交通导向开发(TOD)建设更宜居、可持续城市的工作无疑是个好消息。例如,为了支持最近启动的全球环境基金(GEF)“可持续城市综合方式示范项目”,我们与中国一家主要的共享单车公司“摩拜单车”合作,使用项目城市地铁站周边的骑行路线数据开展研究。以下是一些有意思的发现:
  • 重新审视TOD的范围。关于TOD的核心区域,普遍接受的教科书定义是围绕地铁站或其他公共交通枢纽800米半径的范围。这个定义是基于10分钟步行可达的距离。然而,在骑行普及的丹麦、荷兰等地,地铁站的实际覆盖半径可达2-3公里。我们的分析发现,地铁站周边有一大部分骑行的距离甚至超过3公里半径(见下图1中的亮蓝色轨迹)。这说明地铁站周边区域规划和设计的空间范围应该根据当地环境而定。相应地,由于靠近公共交通服务设施而产生的增值,其影响的房地产范围很可能超出预期。
1:北京(左)和深圳(右)主要地铁站周边的骑行轨

[阅读:中国特色的TOD:因地制宜是通则,而非特例] — 文章也讨论了TOD范围的划定

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