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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.

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

Can Dar es Salaam become the next global model on transit-oriented development?

Chyi-Yun Huang's picture
Photo: World Bank
Public exhibition at Gerezani BRT Station in Dar es Salaam, Tanzania on October 12, 2017.
(Photo: World Bank)

Many urban planners may know the success stories of Curitiba, Singapore or London realizing transit-oriented development (TOD). However, TOD is still very new in Sub-Saharan Africa. Although this concept of leveraging on major transit infrastructure to affect integrated land-use development for greater benefits may be gaining more recognition, there are few examples of successful TOD in Sub-Saharan Africa beyond a couple of South African cities, such as Cape Town and Johannesburg.

Dar es Salaam, Tanzania now has the perfect opportunity to become a pioneer on transit-oriented development.

Dar es Salaam, the largest city in Tanzania with a population of 4.6 million, is expected to become a mega city by 2030 with a population over 10 million. However, its growth has been largely shaped by informality, coupled with a lack of hierarchy in roads and transit modes. It is increasingly difficult to get around the city without being stuck in traffic for hours. The complex and fragmented institutional structure of Dar es Salaam compounds the challenges, making management of the city complicated and less effective.

From Istanbul to Manila—different fault lines, similar challenges

Elif Ayhan's picture
 “It’s not the mountain we conquer, but ourselves.” This was the response given by Sir Edmond Hillary when asked how he and his companion Tenzing Norgay became the first to summit Mt Everest, when so many before had failed. He believed we could all overcome our biggest challenge simply by deciding to act.

Is it possible for the same sentiment to be applied by government leaders – leaders who have the privilege and responsibility to preside over some of the world’s largest and most dynamic cities, especially those that share a common challenge in terms of seismic risk? Metro Manila, the megacity of the Philippines, the seat of government, and the engine of the national economy, has been destroyed numerous times over the last 500 hundred years by earthquakes, and currently sits upon a fault that is overdue to move. Istanbul, with world-class cultural heritage sites treasured by all, also sits near major fault lines expected to move any day. Tokyo and Wellington, the heart of government, culture, and history, also share exposed locations close to major fault lines.

In Wellington, decades of work – including the current Get Ready week! – have aimed to prepare the city for the next “big one”; but compared to the burgeoning megacities of Manila, Tokyo, or Istanbul, it is a small hill to conquer. How do you prepare these megacities with population of up to 15 million people? How do you climb the mountain of needs to build resilience? According to Sir Hillary, the answer is simple, you need to take the decision to accomplish something extraordinary.

In September 2017, the World Bank and the Global Facility for Disaster Reduction and Recovery (GFDRR) through the Japan-World Bank Program for Mainstreaming Disaster Risk Management in Developing Countries supported a knowledge exchange between Turkey and the Philippines focused on the challenge of building seismic resilience in megacities with high urbanization. For the World Bank, it was clear from the start that seismic risk is a priority on the Urban Resilience Agenda, when Johannes Zutt was able to explain to the visiting delegation the technical details of how base isolation is used to protect critical hospitals in Istanbul. The delegation saw impressive progress made by Turkey and Istanbul, from revised institutional frameworks, strengthened preparedness and response capabilities, and retrofitted schools and hospitals to adapted municipal e-services that ensure that the construction of resilient new buildings are approved fast and with the right safety checks. While massive seismic risk still exists within Istanbul, visible and concrete actions are also underway to improve the safety of its citizens.
 
 

 

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