We are moving to a new home: Urban Demographics 2.0

NOTE: This website has moved to a new address at urbandemographics.org. This content has not been updated since April 2020.

After 1530 blog posts and 471 thousand pageviews over a period of 9 years and 10 months, we are moving to Urban Demographics 2.0, at urbandemographics.org. I will keep a frozen version of this blogspot website online for the record, but I won't be updating any content.

Blogger has been a good companion for a long time, but I felt it was time to move on to a more flexible and versatile platform. Urban Demographics 2.0 is entirely written from within R using blogdown and Hugo. You can find more info in the 1st post of the new website :)

If you follow UD updates via RSS, I am trying move our feed to the new website so you don't have to do anything. I hope this won't break things, but this is our new feed if you want to make sure not to miss any new posts. The Twitter and Facebook channels remain unchanged.

See you on the other side

Photo by Toa Heftiba

Soundtrack:

COVID-19 pandemic and access to healthcare in Brazil's largest cities

The Institute for Applied Economic Research (Ipea) published yesterday our study looking at 'Urban mobility and access to the healthcare system by patients with suspected and severe cases of COVID-19 in the 20 largest cities of Brazil'. The work is published in Portuguese but there is a Twitter thread with the main findings. In any case, I included a summary of the publication in English below.

obs. This is a by-product of the Access to Opportunities Project. I'm grateful for an amazing team of co-authors who helped me put this piece together in such a short time.

Summary:

The Covid-19 epidemic crisis is causing a rapid growth in the number of hospitalizations for severe acute respiratory syndrome (SARS) in Brazil. According to recent studies, this could soon overload the country's public health system (SUS). As of this writing, most of the confirmed cases of Covid-19 are concentrated in the country's largest cities, where the spread of the disease is at a rapid pace and affecting a growing number of people in disadvantaged communities.

In this policy report, we analyze accessibility to healthcare services in Brazil's 20 largest cities. The research focuses on how easily patients with suspected and severe cases of COVID-19 could reach public health facilities. The study has two purposes:

1. In the first half of the report we estimate how many vulnerable people (low-income above 50 years old) live in areas with poor access to healthcare facilities that could either screen suspected cases of Covid-19 or provide hospitalization of severe cases with the support of ICU beds and mechanical ventilators.
2. In the second half, we estimate the ratio between the number of ICU beds and mechanical ventilators available at each hospital and the population living withing its catchment area.

These two analyses combined provide actionable information to local authorities. The study puts disadvantaged communities with poor access to health services on the map, indicating in which neighborhoods local authorities could build makeshift hospitals or develop strategies via pre-hospital care with mobile units or through the work of health community agents. This research also helps local authorities identify which hospitals could more likely struggle with the rising demand for hospitalizations, and hence would need investments to expand capacity.

New paper out: Disparities in travel times between cars and public transport

I am very glad to share our new paper looking at the travel time gap between private and public transport at high spatial and temporal resolutions. The study combines real-time traffic data, transit data, and travel demand estimated using Twitter data to compare this travel time gap in four cities (São Paulo, Stockholm, Sydney and Amsterdam).

Despite remarkable differences between these cities in terms of transportation networks, area, and population size, we found travel times of transit and vs. driving are surprisingly similar across cities: R < 1 for trips shorter than 3km, then increases rapidly but quickly stabilizes at 2 (figure below). Moreover, using public transport generally takes on average 1.4–2.6 times longer than driving a car. The share of area where travel time favors public transport over car use is also very small in all cities. As Giulio Mattioli noted on Twitter, these results 'would confirm that car dependence is much more than just a question of culture & attitudes'.

The paper is open access and it was written in collaboration with a great team led by Yuan Liao and Sonia Yeh at University of Chalmers, Sweden.

Liao, Y., Gil, J., Pereira, R.H.M. et al. Disparities in travel times between car and transit: Spatiotemporal patterns in cities. Scientific Reports 10, 4056 (2020). https://doi.org/10.1038/s41598-020-61077-0

Abstract:

Cities worldwide are pursuing policies to reduce car use and prioritise public transit (PT) as a means to tackle congestion, air pollution, and greenhouse gas emissions. The increase of PT ridership is constrained by many aspects; among them, travel time and the built environment are considered the most critical factors in the choice of travel mode. We propose a data fusion framework including real-time traffic data, transit data, and travel demand estimated using Twitter data to compare the travel time by car and PT in four cities (São Paulo, Brazil; Stockholm, Sweden; Sydney, Australia; and Amsterdam, the Netherlands) at high spatial and temporal resolutions. We use real-world data to make realistic estimates of travel time by car and by PT and compare their performance by time of day and by travel distance across cities. Our results suggest that using PT takes on average 1.4–2.6 times longer than driving a car. The share of area where travel time favours PT over car use is very small: 0.62% (0.65%), 0.44% (0.48%), 1.10% (1.22%) and 1.16% (1.19%) for the daily average (and during peak hours) for São Paulo, Sydney, Stockholm, and Amsterdam, respectively. The travel time disparity, as quantified by the travel time ratio R (PT travel time divided by the car travel time), varies widely during an average weekday, by location and time of day. A systematic comparison between these two modes shows that the average travel time disparity is surprisingly similar across cities: R < 1 for travel distances less than 3 km, then increases rapidly but quickly stabilises at around 2. This study contributes to providing a more realistic performance evaluation that helps future studies further explore what city characteristics as well as urban and transport policies make public transport more attractive, and to create a more sustainable future for cities

The relationship between travel distance and travel time ratio R (PT travel time divided by the car travel time)

How much time do we spend with other people as we grow old?

A couple of years ago, I posted this chart showing how much time we spend with other people as we grow old. The chart was created by Henrik Lindberg using data from the America Time Use Survey, and the code to recreate this chart in R is available here.

p.s It's my birthday today and birthdays are always a good moment to reflect about life :)

New paper out: Distributional effects of transport policies on inequalities in access to opportunities

Glad to share our paper on "Distributional effects of transport policies on inequalities in access to opportunities in Rio de Janeiro" is now out the Journal of Transport and Land Use. I summarize the paper findings and contributions in this short thread here, but please feel free to read the full paper. The journal is open access!

Pereira, R. H. M., Banister, D., Schwanen, T., & Wessel, N. (2019). Distributional effects of transport policies on inequalities in access to opportunities in Rio de Janeiro. Journal of Transport and Land Use, 12(1). doi:10.5198/jtlu.2019.1523

Abstract:

The evaluation of social impacts of transport policies has been attracting growing attention in recent years. Yet studies thus far have predominately focused on developed countries and overlooked whether equity assessment of transport projects is sensitive to the modifiable areal unit problem (MAUP). This paper investigates how investments in public transport can reshape socio-spatial inequalities in access to opportunities, and it examines how MAUP can influence the distributional effects of transport project evaluations. The study looks at Rio de Janeiro (Brazil) and the transformations carried out in the city in preparation for the 2014 World Cup and the 2016 Olympics, which involved substantial expansion in public transport infrastructure followed by cuts in service levels. The paper uses before-and-after comparison of Rio's transport network (2014-2017) and quasi-counterfactual analysis to examine how those policies affect access to schools and jobs for different income groups and whether the results are robust when the data is analyzed at different spatial scales and zoning schemes. Results show that subsequent cuts in service levels have offset the accessibility benefits of transport investments in a way that particularly penalizes the poor, and that those investments alone would still have generated larger accessibility gains for higher-income groups. These findings suggest that, contrary to Brazil’s official discourse of transport legacy, recent policies in Rio have exacerbated rather than reduced socio-spatial inequalities in access to opportunities. The study also shows that MAUP can influence the equity assessment of transport projects, suggesting that this issue should be addressed in future research.

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.

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

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).

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.

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.

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.

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

New paper out: Future accessibility impacts of transport policy scenarios: equity and sensitivity to travel time thresholds

I'm glad to share that the 3rd paper of my thesis is now published. The study (1) illustrates how one can measure the future accessibility impacts of transport project scenarios; (2) discusses how accessibility analyses can be influenced by the little-known issue of the modifiable temporal unit problem (MTUP); and (3) shows that equity assessments of transport policies based on cumulative opportunity metrics depend on the time threshold chosen for accessibility analysis. One thing in particular I like about this paper is that its findings demonstrate that the most common practice adopted by academic studies and transport agencies when evaluating the accessibility impacts of transportation projects can lead to misleading or partial conclusions if this methodological choice is made uncritically.

The paper will remain open access for the next 40 days or so. Downloaded it here [ungated preprint]. The R scripts used to write this paper and my PhD thesis are available in this GitHub repo.

Pereira, R. H. M. (2019). Future accessibility impacts of transport policy scenarios: equity and sensitivity to travel time thresholds for Bus Rapid Transit expansion in Rio de Janeiro. Journal of Transport Geography, 74, 321-332.

Abstract: 

The accessibility impacts of transport projects ex-post implementation are generally evaluated using cumulative opportunity measures based on a single travel time threshold. Fewer studies have explored how accessibility appraisal of transport plans can be used to evaluate policy scenarios and their impacts for different social groups or examined whether the results of project appraisals are sensitive to the time threshold of choice. This paper analyzes how different scenarios of full and partial implementation of the TransBrasil BRT project in Rio de Janeiro (Brazil) will likely impact the number of jobs accessible to the population of different income levels. The analysis is conducted under various travel time thresholds of 30, 60, 90 and 120 min to test whether the results are sensitive to the boundary effect of the modifiable temporal unit problem (MTUP). Compared to a partial operation scenario, the full implementation of TransBrasil that extends this corridor into the city center would lead to higher accessibility gains due to network effects of connecting this BRT to other transport modes. Nonetheless, the size of the accessibility impacts of the proposed BRT as well as its distribution across income classes would significantly change depending on the time threshold chosen for the accessibility analysis. Considering cut-off times of 30 or 60 min, both scenarios of TransBrasil would lead to higher accessibility impacts in general and particularly for low-income groups, moving Rio towards a more equitable transportation system. However, under longer thresholds of 90 and 120 min, an evaluation of this project would find much smaller accessibility gains more evenly distributed by income levels. The paper highlights how time threshold choice in cumulative opportunity measures can have important but overlooked implications for policy evaluation and it calls for further research on the MTUP in future transport and mobility studies.

The transport legacy of Mega-Events in Rio favored the richest and was offset by an economic crisis

self-promotion alert 

My PhD research was covered on BBC Brazil today. They present a very good summary (in Portuguese) of some of the main results. If you have insomnia problems  are interested in reading the full thesis, it is available for download here.

image credit: Fernando Frazão/Agência Brasil

Chart of the Day and a Biographical note

I was given this birthday card by my partner yesterday. Isn't she lovely?! This is a great chart  and bit too honest .

I also received yesterday an email I wrote myself five years ago. There is this website FutureMe, which allows you to send an email to your future self. You just have to write a message, point to a destination email address and the date when the email will be received. The email I received yesterday was written right after I had moved to Oxford. It was written by a younger Rafa who was thrilled to start a PhD but also insecure if he belonged to that place, and someone who had lots of questions about how my life would unfold in the following years. I'm glad about the answers I have today for the questions I had back then.

I write these emails to my future self once every two or three years. I find it a great exercise to reflect about life and to keep track of how my thoughts, ideas, fears, plans etc change over time. You should give it a try,

ps. FutureMe is a free website and they didn't pay me to write this post.

PhD thesis officially deposited and available for download

PhD thesis officially deposited! You can download the thesis here and check the R code I used in the data wrangling, mapping and analysis in this GitHub repo.*

ps. Special thanks to my friend Christine Moore for making the deposit.

* If you find any mistakes, let me know and I'll try to find someone to blame for.

Future access to essential services in a growing smart city

Warning of  shameless  self-promotion:

I'm glad to share that some colleagues at UBC (Jerome, Martino and Nuttall) and I have a new paper published. In this paper we analyze how projected population change could affect future accessibility demand to education and healthcare services and transportation equity, looking at the case of Surrey in Canada. One thing in particular I like about this paper is that it looks at how transport accessibility is affected by changes in population growth and spatial distribution while most studies in the literature have traditionally looked at how accessibility levels change due to modifications in the transport network or in the spatial allocation of schools, healthcare facilities etc. The paper will remain open access for the next 50 days. Download it here or send me an email and I'll be glad to share it to you. 

Mayaud, J. R., Tran, M., Pereira, R. H. M., & Nuttall, R. (2018). Future access to essential services in a growing smart city: The case of Surrey, British Columbia. Computers, Environment and Urban Systems. doi:10.1016/j.compenvurbsys.2018.07.005

Abstract:

The concept of accessibility – the ease with which people can reach places or opportunities –lies at the heart of what makes cities livable, workable and sustainable. As urban populations shift over time, predicting the changes to accessibility demand for certain services becomes crucial for responsible and ‘smart’ urban planning and infrastructure investment. In this study, we investigate how projected population change could affect accessibility to essential services in the City of Surrey, one of the fastest growing cities in Canada. Our objectives are two-fold: first, to quantify the additional pressure that Surrey's growing population will have on existing facilities; second, to investigate how changes in the spatial distribution of different age and income groups will impact accessibility equity across the city. We evaluated accessibility levels to healthcare facilities and schools across Surrey's multimodal transport network using origin-destination matrices, and combined this information with high-resolution longitudinal census data. Paying close attention to two vulnerable population groups – children and youth (0–19 years of age) and seniors (65+ years of age) – we analyzed shifts in accessibility demand from 2016 to 2022. The results show that population growth both within and outside the catchments of existing facilities will have varying implications for future accessibility demand in different areas of the city. By 2022, the city's hospitals and walk-in clinics will be accessible to ~9000 and ~124,000 more people (respectively) within a predefined threshold of 30 min by public transport. Schools will also face increased demand, as ~8000 additional children/youth in 2022 will move to areas with access to at least half of the city's schools. Conversely, over 27,000 more people – almost half of them seniors – will not be able to access a hospital in under 30 min by 2022. Since low-income and senior residents moving into poorly connected areas tend to be more reliant on public transport, accessibility equity may decline in some rural communities. Our study highlights how open-source data and code can be leveraged to conduct in-depth analysis of accessibility demand across a city, which is key for ensuring inclusive and ‘smart’ urban investment strategies.

On the road

This blog and my Twitter will be less active in the next few days.

I'm on my way to California to have a few weeks off from work and celebrate. My partner completed her masters degree and I finished my PhD, so that's a good enough reason for us to celebrate. See you next month. 

ps. If you really have nothing else better to read in the meantime, have a look at this wonderful  PhD thesis.

image credit: ?, via @CityDescriber (funny bot by Geoff Boing)

The day I became a Doctor

I'm very glad  and relieved  to share the news that I became a doctor last week! It might take some time for the university to publish my PhD thesis, so I've decided to make the preprint of the thesis available for download here. I've also created a GitHub repository to share the R code used in the data wrangling, mapping and analysis in the thesis.

My examiners were Nihan Akyelken and Bert van Wee. They were super kind but very challenging, nonetheless. In the end, the PhD viva lasted for 2.5 hours and I was super nervous the whole time. I really enjoyed the viva, though, and I was so surprised when they said I had passed with no corrections that I almost jumped out of my chair. I got this result largely because of my incredibly  demanding  tireless supervisors Tim Schwanen and David Banister, to whom I'm extremely grateful.  All in all, I'm feeling incredibly happy and thankful for the whole journey and the support I received along the away from my family, friends and supervisors. It’s been a truly wonderful and humbling experience.

ps. I still have two papers of the thesis currently under review, but finishing the PhD means that now I'll have much more time to  procrastinate  work on new projects and some others that were put on hold.

photos by my lovely wife, Fabiana - also known as my third supervisor :)

Biographical note: back to the library

Working from the Oxford Bodleian Library and the Radcliffe Camera these days. Getting ready to my PhD defence and the seminar at UCL next week. The blog has been less active these days but I hope to post some good news in the coming days.

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