Monday, August 19, 2019

The influence of ride-hailing on users' travel behavior

New paper hot off the press, by Alejandro Tirachini (Twitter).

Tirachini, A., & del Río, M. (2019). Ride-hailing in Santiago de Chile: users’ characterisation and effects on travel behaviour. Transport Policy. Volume 82, October 2019, Pages 46-57

In this paper, an in-depth examination of the use of ride-hailing (ridesourcing) in Santiago de Chile is presented based on data from an intercept survey implemented across the city in 2017. First, a sociodemographic analysis of ride-hailing users, usage habits, and trip characteristics is introduced, including a discussion of the substitution and complementarity of ride-hailing with existing public transport. It is found that (i) ride-hailing is mostly used for occasional trips, (ii) the modes most substituted by ride-hailing are public transport and traditional taxis, and (iii) for every ride-hailing rider that combines with public transport, there are 11 riders that substitute public transport. Generalised ordinal logit models are estimated; these show that (iv) the probability of sharing a (non-pooled) ride-hailing trip decreases with the household income of riders and increases for leisure trips, and that (v) the monthly frequency of ride-hailing use is larger among more affluent and younger travellers. Car availability is not statistically significant to explain the frequency of ride-hailing use when age and income are controlled; this result differs from previous ride-hailing studies. We position our findings in this extant literature and discuss the policy implications of our results to the regulation of ride-hailing services in Chile.


Monday, August 12, 2019

geobr: easy access to official spatial data sets of Brazil

I'm glad to annouce that geobr is now officially available on CRAN. Here and here are quick intros on how to use geobr to get easy and quick access to shape files and other official spatial data sets of Brazil. The package currently includes several data sets for various years such as states, regions, municipalities, census tracts, statistical grid and others. The github repository is this, in case you want to keep track of the latest developments.

The package was developed by my team and I at the Institute for Applied Economic Research (Ipea). We are constantly working to expand and improve the package, so if you have any suggestions/contributions, please feel free to open an issue on Github.

Friday, July 26, 2019

Climate change and the glass half full

Quote of the day:
"Some people complain that this is the hottest summer in the last 125 years, but I like to think of it as the coolest summer of the next 125 years! Glass half full!" (Carter Bays)

Thursday, July 25, 2019

A spatial database of health facilities in sub Saharan Africa

Interesting new paper analyzing accessibility to emergency hospital care in sub-Saharan Africa in 2015. The authors have done a laborious work to map public health facilities and the data is openly available here. HT Moritz Kraemer.

Timely access to emergency care can substantially reduce mortality. International benchmarks for access to emergency hospital care have been established to guide ambitions for universal health care by 2030. However, no Pan-African database of where hospitals are located exists; therefore, we aimed to complete a geocoded inventory of hospital services in Africa in relation to how populations might access these services in 2015, with focus on women of child bearing age.
We assembled a geocoded inventory of public hospitals across 48 countries and islands of sub-Saharan Africa, including Zanzibar, using data from various sources. We only included public hospitals with emergency services that were managed by governments at national or local levels and faith-based or non-governmental organisations. For hospital listings without geographical coordinates, we geocoded each facility using Microsoft Encarta (version 2009), Google Earth (version 7.3), Geonames, Fallingrain, OpenStreetMap, and other national digital gazetteers. We obtained estimates for total population and women of child bearing age (15–49 years) at a 1 km2 spatial resolution from the WorldPop database for 2015. Additionally, we assembled road network data from Google Map Maker Project and OpenStreetMap using ArcMap (version 10.5). We then combined the road network and the population locations to form a travel impedance surface. Subsequently, we formulated a cost distance algorithm based on the location of public hospitals and the travel impedance surface in AccessMod (version 5) to compute the proportion of populations living within a combined walking and motorised travel time of 2 h to emergency hospital services.
We consulted 100 databases from 48 sub-Saharan countries and islands, including Zanzibar, and identified 4908 public hospitals. 2701 hospitals had either full or partial information about their geographical coordinates. We estimated that 287 282 013 (29·0%) people and 64 495 526 (28·2%) women of child bearing age are located more than 2-h travel time from the nearest hospital. Marked differences were observed within and between countries, ranging from less than 25% of the population within 2-h travel time of a public hospital in South Sudan to more than 90% in Nigeria, Kenya, Cape Verde, Swaziland, South Africa, Burundi, Comoros, São Tomé and Príncipe, and Zanzibar. Only 16 countries reached the international benchmark of more than 80% of their populations living within a 2-h travel time of the nearest hospital.
Physical access to emergency hospital care provided by the public sector in Africa remains poor and varies substantially within and between countries. Innovative targeting of emergency care services is necessary to reduce these inequities. This study provides the first spatial census of public hospital services in Africa.

Wednesday, July 10, 2019

Off to the UK

I'm off to the UK to participate in my graduation ceremony at Oxford and to celebrate my partner's graduation at  Cambridge  the other place. Really excited because both our parents will be there to celebrate with us. Yep, this will require some serious diplomatic skills, though :)

My graduation will happen this Saturday, on July 13th between 11am and 12pm. So, you will be able to see a bunch of academics weirdly dressed wondering around Oxford at 12pm on that day. You can actually see this through the live webcam of the Oxford Martin School in case you really need something to procrastinate with.

ps. Blog activity will be low over the next couple of weeks but you'll probably see me Tweeting regularly while I'm queuing for something somewhere in England.

Tuesday, July 9, 2019

We're hiring research assistants to work with Spatial Data Science at Ipea

A few readers might be interested in this post. We are hiring 4 research assistants to work with (spatial) data science on urban, regional and environmental research and policies at the Institute for Applied Economic Research (Ipea), in Brasília. Great team with lots of computational resources, rich data sets and plenty of challenging data analyses to improve public policies.

*** All the positions are based in Brasília, Brazil.

Sunday, July 7, 2019

Music for the weekend

Soundtrack for a weekend of good bye to João Gilberto, one of the fathers of Bossa Nova. A Brazilian giant.

Thursday, July 4, 2019

The winners and losers of the transport legacy of megaevents

Summarizing the core elements of one's research to communicate with a wide audience is among the most challenging and yet important aspects of what researchers do. Here's my best attempt so far to summarize my PhD research to a broad audience, published in my favorite online newspaper Nexo. The text is in Portuguese.

image credit: Nexo

Monday, July 1, 2019

geobr: shapefiles and official spatial data sets of Brazil in R

In 2012, I published here a blog post about where to find shapefiles of Brazil. Since then, this has become one of the most popular posts in 9 years of the blog. However, the links to the original data sets change every now and then, and it gets a bit tricky to find the most up to date data. My team and I at the Institute for Applied Economic Research (Ipea) have created geobr, an R package that allows users to easily access shapefiles of the Brazilian Institute of Geography and Statistics (IBGE) and other official spatial data sets of Brazil.

The geobr package currently includes a variety of data sets, such as the shapefiles of municipalities and states (from 1872 to 2018), census weighting areas, a spatial grid with population count at a resolution of 200 x 200 meters, a geolocated database of health facilities in the country etc. All the data sets are read into R as sf data. We will gradually add other databases to the package, but feel free to make specific requests and suggestions by opening new issues on the GitHub page of geobr or tweeting the hashtag #geobr.

The advantage of geobr: Intuitive syntax that provides easy and quick access to a wide variety shapefiles and official spatial data sets with updated geometries for various years using harmonazied attributes and geographic projections across geographies and years.

Here is a quick intro to geobr:

Sunday, June 30, 2019

Interactive visualization of large-scale spatial data sets in R

In the beginning, there were only static maps. Over the past years we have seen the creation of new packages like mapview and mapedit that allow one to interactively visualize and edit spatial data in R. Despite these developments, it was still a bit tricky to visualize large spatial data sets in R. Not anymore.

Two packages that are pushing our capabilities to interactively visualize large-scale spatial data sets in R:

Hats off to these two! 👏👏👏



Wednesday, June 26, 2019

9th Anniversary of Urban Demographics !

Today is the 9th Anniversary of Urban Demographics. I must say the blog has never been as quiet as in the past year. This is due to various reasons. I focused a lot of my time over the past year in finishing my PhD, getting back to work on project/paper collaborations that had been on hold for a long time and perhaps I spent too much time travelling. Sorry, family. Sorry, planet. Personally and professionally, though, it has been an incredible year. I've finally became a doctor (1st in the family, Mom was very proud), I received awards from the AAG and the ITF/OECD, got a few studies published, I've met a bunch of incredible people, and started a few new projects that I'm very excited about and which I'll be sharing here in due time.

Nowadays, I spend less time  procrastinating  working on the blog than on Twitter, which I find an increasingly rich source of dog pictures information and interaction with other researchers. In the end, the blog has been a bit quite but I still find it incredibly useful to share interesting studies, data, links etc. By the stats of the blog, I'm glad to see a few people still find it useful too. Here are just some quick stats that show a summary of the blog over the past year.

and 10 of my favorite posts:

Where do readers come from? (140 countries | 2,598 Cities)
  1. United States (32.3%)
  2. Brazil (13%)
  3. United Kingdom (6.3%)
  4. Australia (3.5%)
  5. Canada (3.4%)

Friday, June 21, 2019

Who pollutes and who gets exposed to road traffic-related air pollution in the UK

In 2003, Gordon Mitchell and Danny Dorling published "An environmental justice analysis of British air quality", a widely cited paper that became a key reference in the environmental justice literature. Now, 16 years latter, a new paper by Joanna Barnes (Twitter), Tim Chatterton (Twitter) and James Longhurst update the original study with new data and more in depth analysis on the social inequalities in traffic-related pollution exposure and emission.

Barnes, J. H., Chatterton, T. J., and; Longhurst, J. W. (2019). Emissions vs exposure: Increasing injustice from road traffic-related air pollution in the United Kingdom. Transportation Research Part D: Transport and Environment, 73, 56-66.

This paper presents unique spatial analyses identifying substantial discrepancies in traffic-related emissions generation and exposure by socioeconomic and demographic groups. It demonstrates a compelling environmental and social injustice narrative with strong policy implications for the UK and beyond.
In the first instance, this research presents a decadal update for England and Wales to Mitchell and Dorling’s 2003 analysis of environmental justice in the UK. Using 2011 UK Government pollution and emissions data with 2011 UK Census socioeconomic and demographic data based on small area census geographies, this paper demonstrates a stronger relationship between age, poverty, road NOxemissions and exposure to NO2 concentrations. Areas with the highest proportions of under-fives and young adults, and poorer households, have the highest concentrations of traffic-related pollution.
In addition, exclusive access to UK annual vehicle safety inspection records (‘MOT’ tests) allowed annual private vehicle NOx emissions to be spatially attributed to registered keepers. Areal analysis against Census-based socioeconomic characteristics identified that households in the poorest areas emit the least NOxand PM, whilst the least poor areas emitted the highest, per km, vehicle emissions per household through having higher vehicle ownership, owning more diesel vehicles and driving further.
In conclusion, the analysis indicates that, despite more than a decade of air quality policy, environmental injustice of air pollution exposure has worsened. New evidence regarding the responsibility for generation of road traffic emissions provides a clear focus for policy development and targeted implementation.

Related post:

credit: Barnes et al 2019

Monday, June 17, 2019

Assorted links

  1. 25% of students think they are in the top 1% of social skills. 94% of professors think their work is better than their peers. The Social Psychology of Biased Self-Assessment (ht Leo Monasterio)

  2. What happened when New York City (randomly) increased street lighting? Crime fell by 36% as a direct result. HT John B. Holbein ‏, who is great at finding this kind of gems by the way.

  3. Sacred Spaces: a series on modernist churches' by Thibaud Poirier, HT Darran Anderson

  4. Interesting report comparing housing in London , New York City, Paris and Tokyo, by Jim Gleeson. Some key results summarized in this short thread.

  5. The power of a single book. Beautiful metaphor for how ideas can have real impact

  6. The data that was missing in your research: an incredibly detailed 3-D maps of the lunar surface

  7. Microsoft Researchers trained a neural network to analyze satellite imagery and generate the footprints of 125,192,184 building in all 50 US states. The data are available on GitHubGreat coverage in the NYT, by Tim Wallace et al.

image credit: NYT

The suburbs of Mesa, Arizona

image credit: NYT

Wednesday, June 5, 2019

What The Simpsons got right about Transport Planning

Many of you will remember that "Marge vs the Monorail" episode of The Simpsons*. Juliet Eldred has written a hilarious and thoughtful Twitter thread about how this episode encapsulates a lot of the common issues in Transportation Asset Management faced by transport agencies. Good food for thought about the dynamics of policy decision making, the creation of white elephants, and how routine maintenance gets sidestepped by the  hype of 'new' technologies and capital investment. This story speaks a lot to recent transport projects worldwide, including the silly idea of Elon Musk's tunnel project.

* If you haven't watched it before, waste no more time. Watch it here. You're welcome :)

Friday, May 31, 2019

More evidence on the health benefits of active transport

“Women who averaged approx. 4400 steps/d had significantly lower mortality rates [..] compared with the least active women who took approx. 2700 steps/d; as more steps per day were accrued, mortality rates progressively decreased before leveling at approximately 7500 steps/d.”

This is from a new paper that just came out in JAMA (via Eric Topol). And yes, the authors are have addressed reverse causation bias. Read the methods section.

Fig. Dose-Response Association Between Mean Steps per Day and All-Cause Mortality

Wednesday, May 29, 2019

My presentation at the 2019 ITF Summit

shameless self-promotion post  again 

Last week I was attending the 2019 International Transport Forum Summit, where I presented a paper on estimating the future accessibility impacts of transport project scenarios. The study also discusses the equity implications of travel-time threshold choice in cumulative opportunity metrics. Such a sexy topic, ah.

My presentation was recorded and you can watch it here (in case you really need to procrastinate on the work you should be doing now).

Monday, May 27, 2019

How congestion pricing works in London and how it could soon work in NYC

New York city is closer than ever to adopt congestion pricing. This could be a major change in how they address their transportation challenges and fund public transport. A team at Vox made an informative video about this, and they asked the sharp Nicole Badstuber (Twitter) to explain how congestion pricing works in London. London started charging private vehicles to enter the city center in 2003. Last month they enacted the London’s ultra-low emission zone, which adds another charge for most vehicles manufactured before 2015.

Saturday, May 18, 2019

Biographical note: ITF/OECD award

Hi all. I am so glad to share that I have been honored with the 2019 Young Researcher of the Year Award, by the International Transport Forum (ITF/OECD). As I've said many times, this award speaks volumes about the generous guidance and support I have received from supervisors and colleagues at both Oxford and Ipea to conduct my research. Special thanks to my incredibly  demanding  supportive supervisors Tim Schwanen and David Banister. Thanks!

This is the award-winning paper, where I investigate the future impacts that different scenarios of a major BRT in Rio de Janeiro could have on access to employment opportunities for different income groups. The study also shows that the the equity assessment of transport projects based on accessibility estimates using cumulative opportunity measures with a single time threshold (the most common practice adopted by academic studies and transport agencies) can lead to misleading or partial conclusions. The preprint of the study is available for download here (it includes a spatial regression analysis that didn't make it into the paper because or reviewer #2).

Thanks to the award, I'll be attending the 2019 International Transport Forum Summit in Leipzig next week. The team at ITF will be Twitting about the Summit. I'll be presenting the paper on May 23rd at  5:15pm (local time). Apparently, it will be webcasted on Facebook Live.

Wednesday, May 8, 2019

The reasons two variables can be correlated

A concise illustration, by Thomas Lumley. This reminded me of this quite comprehensive list of some  ridiculous  spurious correlations.

image credit: Thomas Lumley

Friday, May 3, 2019

R Links

  1. The ipumsr package helps import census and survey data from around the world integrated across time and space. I've mentioned IPUMS in the blog before. This is certainly among the most important, ambitious and succeeded open data projects in the world

  2. A rather comphrensive comparison between data.table and dplyr syntaxes and funcitonalities ht via Mara Averick. I have to say I a strong preference for data.table because of computational performance. I also generally find the data.table syntax more easily readable than dplyr. There, I said.

  3. Free Book with code: “Spatio-Temporal Statistics with R,” by Christopher K. Wikle, Andrew Zammit-Mangion, and Noel Cressie

  4. brickr: a package to Build 3D LEGO models in R, by Ryan Timpe

  5. trackeR: a package for handling running and cycling data from GPS-enabled tracking devices, by Hannah Frick

  6. A Cheat Sheet on how to use the Reticulate package for interoperability between Python and R

  7. How to create a gif of a spinning globe using R, by James Cheshire

  8. The R package traveltime allows one to retrieve travel-time information from the Traveltime Platform API to create isochrone maps like these below. Great work by Thomas Russo.

image credit: Thomas Russo

Off to Sweden

Professor Sonia Yeh (Twitter) was awarded with the Håkan Frisingers scholarship for her innovative research on sustainable transport and energy systems. The award is given by the Volvo Research and Educational Foundations (VREF) and the award ceremony will be held next week on May 6 in Gothenburg. Sonia has kindly invited Yusak Susilo and I to join her in the ceremony to celebrate her work and to deliver a public lecture. The program of the event is available here. We will also have a more academic oriented seminar at Chalmers University on May 7 in the morning, for those around. I'll be mostly talking about future directions on accessibility and equity concerns in transport research and policy. Needless to say I am very glad for Sonia's well deserved award and honored by her invitation.

After that I'll be joining some colleagues from Lund University to deliver a seminar at the The Swedish Knowledge Centre for Public Transport (K2) on May 10 at 9h20. We'll be talking about Transport Justice Perspectives: Comparing Calculated and Perceived Accessibility. Pop in if you're in the neighbourhood.

Monday, April 29, 2019

New Center for Demographic Science at Oxford

Oxford University has recently launched the Leverhulme Centre for Demographic Science (they are also on Twitter). The center is led by Melinda Mills and it involves a team with several top researchers dedicated to seven interconnected research programmes:

1. Nowcasting: digital and computational demography
2. Environmental context, demography and climate change
3. Inequality and diversity
4. Sociogenomics: nature and nurture
5. Causal demography
6. Demography, society and global sustainability
7. Ethics, truth and trust

*** The other good news is that they are hiring Assistant Professors and Postdocs. The center also offers scholarships for Masters and PhD students.

Friday, April 26, 2019

The global population pyramid from 1950 to 2100

New piece by Max Roser in Our World in Data, showing how global demography has changed and what we can expect for the 21st century.

In this figure below, curves in blue to green show how the global population pyramid changed from 1950 to today, while shades of yellow show the UN projections for the change expected until 2100.

click on the image to see full size

Friday, April 19, 2019

The rapid growth of shared bikes and e-scooters in the US

In 2018, people took 84 million trips using shared bikes and e-scooters in the US, an astounding growth in the past year largely due to e-scooters. This number and many other interesting stats come from a new report looking at Shared Micromobility in the US in 2018, recently published by the US National Association of City Transportation Officials (NACTO). Hat tip to Tim Papandreou.

Monday, April 15, 2019

Collaborative mapping of paratransit and GTFS data

Jacqueline Klopp (Twitter) and Clemence Cavoli (Twitter) have a new paper reviewing some trends in transportation planning in African cities with a focus on paratransit. The paper also discusses why official transportation planning should engage with paratransit services and how this task can be supported through collaborative mapping projects that open new avenues for data accountability.

The paper is open access (see link below) and it draws attention to, an initiative working "to scale up these mapping efforts and promote open data and sharing, open source tools and exchange and learning between African cities to build local data infrastructure, eco-systems and local capacities". Thanks to this initiative, one can easily find for example the GTFS data of cities such as Nairobi, Maputo, Accra and Cairo and others. Jackie and others are working to build a similar initiative in Latin America and I hope I will soon bring more info about this. Stay tuned.

Klopp, J. M., & Cavoli, C. (2019). Mapping minibuses in Maputo and Nairobi: engaging paratransit in transportation planning in African cities. Transport Reviews, 1-20.

Often called paratransit because of their flexible stops, schedules and routes, minibuses make up the bulk of public transport in African cities. Despite their ubiquity and importance, these systems are poorly understood by transportation planners who tend to focus on large-scale urban infrastructure projects such as highways, commuter rail or bus rapid transit systems. The assumption within much of this planning is that these minibus systems are barriers to change and will become at most secondary “feeder” buses within large-scale projects, but structured plans detailing this vision are lacking. This paper argues that frequent failure to collect data and value important paratransit systems as a critical part of transportation in their own right is deeply problematic from the point of view of equity, access and inclusive and effective planning. We ask whether the growing number of bottom up mapping projects of minibus systems can disrupt this status quo. By comparing two mapping projects, Digital Matatus in Nairobi and the Mapa Dos Chapas in Maputo, we find that inclusive, collaborative mapping can help render these minibuses more visible in planning and provoke more grounded and inclusive “planning conversations” on multi-modal integration, passenger information and minibus upgrading, all key but relatively marginalised aspects of creating accessible, low emission, high quality and safe public transport in African cities.

Thursday, April 11, 2019

Biographical note: AAG PhD thesis award

I am very pleased to share that my PhD thesis was awarded the best 2019 thesis award by the Transportation Geography Specialty Group of the American Association of Geographers (AAG). I am also very honoured that I was nominated a board member of the specialty group. If it could be of interest, my thesis is available for download here and I've created a GitHub repository with the R code used in the data wrangling, mapping and analysis in the thesis. Some of the chapters in the dissertation have been published as papers here, here and here (+ this other one currently under review).

I am very grateful for the the support from my partner Fabiana, from the Institute for Applied Economic Research (Ipea) and to the invaluable guidance from my  demanding  tireless supervisors Tim Schwanen and David Banister

ps. the blog has been less active than usual in the past weeks because I was away attending the AAG annual meeting to receive the award and to present this paper here.

Wednesday, April 10, 2019

off-topic: The first-ever picture of a black hole

Just a few years ago, Katie Bouman (then a PhD student at MIT) presented this TED talk about the massive collective research effort involved in the Event Horizon Telescope Collaboration. Three years latter, today, this collaboration announced the first-ever picture of a black hole. Katie led the creation of a new imaging algorithm that helped make this possible.

Yep, they have found a way to register the image of a black hole that is about 55 million light years away from Earth. The method is truly inventive, involving an array of telescopes across the globe, atomic clocks, cutting edge machine learning and more than 5 petabytes of data. You can see more about it in this short video or in the public announcement made today.

I know this is a bit off-topic in this blog but my inner nerd child is too excited to let this one pass. This is a big day.

Credit: Event Horizon Telescope Collaboration

Sunday, March 24, 2019

GTFS rotuer in R

For those interested in public transport research and planning, there is a new R package to do public transport routing using GTFS data. The gtfs-router package uses the power of C++ and it is quite efficient. This is only the release version of the package (0.01), though. There is a lot of room for improvements but I hope gtfs-router becomes a strong competitor to OpenTripPlanner in a couple of years.

The package was created by Mark Padgham (twitter), who is the author of/contributor to various other transport-related packages such as dodgrbikedata and osmdata. Kudos to Mark!

ps. The capabilities of R for transport research and planning are greater than never. There is a very vibrant and active community with dozens of other packages. Perhaps this should be the topic for a future post.

image credit: Rstudio and smtd

Thursday, March 21, 2019

Ipea Seminar - Infusing Urban and Regional policy with Geographic Data Science

Today we are having Dani Arribas-Bel (Geographic Data Science Lab, University of Liverpool) presenting a seminar at the Institute for Applied Economic Research (Ipea). Daniel (websiteTwitter) will be talking about his research agenda on "Infusing Urban and Regional policy with Geographic Data Science". The seminar will start at 3pm (local time). My apologies this post comes in short notice. This week has been hectic.

Daniel is part of the development team of  PySAL and he is a prolific researcher and also a great enthusiast of open data/software and research reproducibility. In fact, many of his papers (code and data) and teaching material are available on his Github repo.

Summary of the presentation:
The recent explosion in availability of new forms of data poses significant opportunities to how we analyse cities and regions, both in academic and policy contexts. Over the last decade, three families of data have emerged in this context. One is digital traces of individual activity. From credit card transactions, to mobile phone calls, to thoughts and feelings we decide to share through social media, more and more bits of our life are being stored digitally as data that a computer can understand. The second comes from an increasing number of sensors, from traffic controllers to nano-satellites orbiting the Earth, which are constantly recording information about the environment. The third one has existed for longer but has not been available until recently: a few years ago, governments started releasing data on their internal operations that used to be parked in (closed) silos. This presentation will walk through several examples where new forms of data are applied to tackle new questions or obtain new perspectives on long-standing challenges of regional and urban analysis. As part of this whirlwind tour, we will also spend some time trying to understand what the main challenges, methodological advances, and risks that "accidental data” pose are, and will emphasise the tremendous opportunities they unleash.

credit: Dani Arribas-Bel

Tuesday, March 19, 2019

The race for the largest city in the world over the past 500 years

In previous posts, I've pointed out to an incredible open dataset with comprehensive population estimates of human settlements and cities for the past 6,000 years. The talented John Burn-Murdoch used some of these data to create this nice animation showing the changing ranks of the 10 largest cities in the world since 1500. The full code for the animation is available here.

Friday, March 15, 2019

Creating a simple world map of cities in R

Mike (from cool but useless) asked on twitter if there is any package in R with with lats/longs of lots of cities. In fact there is. Here is a simple code to create a world map of cities with population larger than 40K in R using maps::world.cities and ggplot2.

ps. These population data in the maps package refers to 2016 estimates. If you want city population data from previous years, you might remember that we have previously posted about this open dataset with 6,000 years of global urbanization.

Wednesday, March 13, 2019

Racial inequity in who pollutes and who gets exposed to pollution

A recent paper led by Chris Tessum (University of Washington) and published in PNAS brings novel estimates of racial-ethnic disparities in air pollution cause and exposure in the US. They find that air pollution is disproportionately caused by consumption by white Americans, but disproportionately affects Black and Hispanic Americans. The air pollution input-output model used in the paper is freely available and there's an experimental live version of the model running, here. (thanks Marko Tainio for pointing to this paper)

Fine particulate matter (PM2.5) air pollution exposure is the largest environmental health risk factor in the United States. Here, we link PM2.5 exposure to the human activities responsible for PM2.5 pollution. We use these results to explore “pollution inequity”: the difference between the environmental health damage caused by a racial–ethnic group and the damage that group experiences. We show that, in the United States, PM2.5 exposure is disproportionately caused by consumption of goods and services mainly by the non-Hispanic white majority, but disproportionately inhaled by black and Hispanic minorities. On average, non-Hispanic whites experience a “pollution advantage”: They experience ∼17% less air pollution exposure than is caused by their consumption. Blacks and Hispanics on average bear a “pollution burden” of 56% and 63% excess exposure, respectively, relative to the exposure caused by their consumption. The total disparity is caused as much by how much people consume as by how much pollution they breathe. Differences in the types of goods and services consumed by each group are less important. PM2.5 exposures declined ∼50% during 2002–2015 for all three racial–ethnic groups, but pollution inequity has remained high.

credit: Tessum et a..

Saturday, March 2, 2019

Off The Road

It's Carnaval season in Brazil and I'll be in small fisherman village mostly disconnected. The level of activity in the blog will remain lower than usual this week (my Twitter is probably be less affected though).

Marau, Bahia, Brazil

Tuesday, February 26, 2019

TSU/Oxford is recruiting a Departmental Research Lecturer

The Transport Studies Unit (TSU) and the School of Geography and Environment are recruiting a Departmental Research Lecturer. This post is a full-time, 5-year departmental appointment, research intensive position (75% research). More details here.

TSU is a relatively small research group with some brilliant researchers in an incredibly vibrant department at one of the top universities in the world. This is a great opportunity and I would strongly encourage competitive candidates to apply. The closing date  is 29-Mar-2019.

Wednesday, February 20, 2019

How Barcelona is taking city streets back from cars

The team at Vox have produced some interesting videos on urban-related topics. I've posted a few of them here in the blog before. This one below covers the urban planning in Barcelona, which uses superblocks as a means to build more liveable and inclusive urban environments in parts of the city.

This video is actually from 2 years ago but I only saw this video last week (thanks to the recommendation of  Telmo Amand, who was my high-school geography teacher!)

Tuesday, February 19, 2019

Evidence-based transport planning - event in Rio

In case you're around Rio de Janeiro this Feb 21-22, I'll be joining members of ITDP Brazil and others in a conversation about evidence-based transport planning, GTFS data and accessibility modelling. The event will be broadcast live (in Portuguese) at

On the second day, before the closing of the event, I will give a short presentation on the Access to Opportunities Project, the first steps of the project and our plans for the next couple of years. The program of the event (in Portugese) is in these images below. Click on them to enlarge the image. 

Friday, February 15, 2019

Tuesday, February 5, 2019

Urban Picture

A very cold Chicago (2019), processed by Pierre Markuse using Copernicus Sentinel data.

Thursday, January 31, 2019

Travel time to closest healthcare facility in Rio de Janeiro

The map shows how long it takes (in minutes) to travel by public transport and walking to the closest healthcare facility across the city of Rio de Janeiro. The analysis is disaggregated for facilities providing low-, medium- and high-complexity services. 

The first thing to note here is that physical accessibility to public health is relatively high in Rio. Approximately 94% of Rio`s population could reach at least one facility providing low-complexity services under 30 minutes. Under the same time, medium- and high-complexity services could be reached by 81% and 72% of the population, respectively. This is explained to some extent by the spatial planning of healthcare in the region, which has been relatively successful in spreading low- and medium-complexity facilities across the city. The map also gives a good sense of how the distribution of healthcare facilities vis-à-vis the public transport network varies across space, and how access to public health tend to be much lower in the west and particularly in the urban fringes of the city.

ps. This is a map I created for my PhD research but I didn't include it in the thesis in the end . To create this map I used a 2015 dataset of healthcare facilities and the GTFS of Rio's public transport network from March 2017. The dataviz and data wrangling were done in R. In case you're interested in doing similar analyses, I've created a simple tutorial with reproducible example on how to use OpenTripPlanner (OTP) to estimate travel times.

[click on the image to enlarge it]

Thursday, January 24, 2019

Why you should probably share your preprints

Among researchers, a preprint is known as the version of a scientific study that precedes official publication in a peer-reviewed journal or book. In hard sciences and computer science, it is quite common for researchers to put their preprints openly available online, mainly through the Arxiv repository. This practice is also common in Economics, where researchers often publish 'working papers' via SSRN, NBER or their own institutions before getting the paper published in a journal. This practice is becoming more common and there are new repositories popping up in different areas such as biorxiv, chemrxiv and the SocArXiv focused on the social sciences more broadly.

Why you should share your preprints:
Preprints are not meant to replace peer-reviewed publications. Nonetheless they can importantly contribute to (1) speeding up the process of getting your ideas out in the public, (2) increasing the readership of your work, and (3) making your research accessible to people who cannot read articles behind paywalls. I've been sharing the preprints of my last papers on SocArXiv and highly recommend others to do the same. There are a few good reasons to use SocArxiv. One of them is that they create a permanent link and a permanent DOI identification for you preprint. This helps making the manuscript searchable and citable on academic databases.

Be aware, though, that some journals for example do not allow the use of preprints as they claim that this practice undermines the novelty of manuscripts. As a rule, though, social science journals published by Elsevier and Taylor & Francis (Routledge) do not see any problem in authors sharing their preprints before paper submission. There is also an interesting debate about whether preprints undermine the double-blindness of peer review and the differential impacts it might have for the publications of senior and junior researchers. As I've mentioned before, the use of preprints is not without controversy. 

Wednesday, January 16, 2019

The Schrödinger Professor

This permanent/temporary position is also indicated in the author's profile on Google Scholar (I saw this on Twitter via the brilliant Drunkeynesian).