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).

Wednesday, January 9, 2019

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.



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.

Sunday, January 6, 2019

Call for a research assistant in the Access to Opportunities Project at Ipea, Brazil


This is just a reminder that I am hiring a research assistant for the Access to Opportunities Project, at the Institute for Applied Economic Research (Ipea). The researcher will be based in Brasilia (Brazil). We are looking for someone with advanced skills in R. Applications will be open until the 20th of January 2019. More details can be found here (info in Portuguese only). Please, help spread us the word.



More info about the Access to Opportunities Project: The aim of the project is to estimate accessibility to employment opportunities as well as education and health services in the largest urban areas in Brazil. The project focuses on how social and spatial inequalities in access to opportunities relate to urban transportation, housing and land use policies. We are estimating accessibility by public transport, walking and cycling at a high spatial resolution for all of the Brazilian major cities. The project will generate a massive amount of data each year. My plan is to make the data outputs and results publicly available to policy makers and researchers, with whom we will be able to collaborate in the future to analzye particular case studies in Brazil but also to conduct comparative studies involving cities in Brazil and other countries.

Thursday, January 3, 2019

A 195 gigapixel Urban Picture of Shanghai

On this link you can browse around an incredible bird's-eye panorama of Shanghai. The picture has an incredible resolution of 195 gigapixels, which captures tiny details such as people's faces or car plates (ht Lionel Page).


image credit: Billion Pixel Studio