Tuesday, April 26, 2016

Traffic Inducing Traffic

Friday, April 22, 2016

Testing Jane Jacobs's ideas on urban vitality using mobile phone data

In her influential book - The Death and Life of Great American Cities (1961), Jane Jacobs proposed that cities would only develop vibrant activities and flourish if they met four conditions of diverse urban environment:
  1. City districts should serve more than one primary function, what would attract people with diverse purposes at different times of the day; 

  2. Street blocks must be short, to allow pedestrian-friendly environments;

  3. The buildings in a district should be diverse in terms of age and form, what would support diversity of economic activities and residents with of high- and low-income;

  4. A district must have a sufficient density of people and buildings; what would foster “lively” environments that attract people for different purposes.

These conditions have recently been tested in four Italian cities in a paper by De Nadai and colleagues (2016). The authors use a combination of data sources, including socio-demographic information from the Italian Census, Open Street Map and human activity patterns extracted from mobile phone data. Good food for thought !

De Nadai, M. et al. (2016). The Death and Life of Great Italian Cities: A Mobile Phone Data Perspective. In Proceedings of the 25th International Conference on World Wide Web (pp. 413-423). International World Wide Web Conferences Steering Committee.
The Death and Life of Great American Cities was written in 1961 and is now one of the most influential book in city planning. In it, Jane Jacobs proposed four conditions that promote life in a city. However, these conditions have not been empirically tested until recently. This is mainly because it is hard to collect data about "city life". The city of Seoul recently collected pedestrian activity through surveys at an unprecedented scale, with an effort spanning more than a decade, allowing researchers to conduct the first study successfully testing Jacobs's conditions. In this paper, we identify a valuable alternative to the lengthy and costly collection of activity survey data: mobile phone data. We extract human activity from such data, collect land use and socio-demographic information from the Italian Census and Open Street Map, and test the four conditions in six Italian cities. Although these cities are very different from the places for which Jacobs's conditions were spelled out (i.e., great American cities) and from the places in which they were recently tested (i.e., the Asian city of Seoul), we find those conditions to be indeed associated with urban life in Italy as well. Our methodology promises to have a great impact on urban studies, not least because, if replicated, it will make it possible to test Jacobs's theories at scale.

ps. You might want to follow some of the authors on twitter: De Nadai, Staiano, Quercia and Lepri.

credit: De Nadai, M. et al. (2016).

Wednesday, April 20, 2016

Creating tilted and stacked maps in R using ggplot2

I've just created a gist showing how to creating tilted and stacked maps in R using ggplot2 in two steps. This was only possible thanks to Barry Rowlingson, who got the solution of the 1st step (which is 90% of the task). Here is how to do it:

Sunday, April 17, 2016

Saturday, April 9, 2016

Chart of the Day

Monday, April 4, 2016

A long-term historical perspective of urban growth in Europe and the US

Marcelo Medeiros (who is secretly my guru) pointed me out to two papers on a long-term historical perspective of urban growth, by Rafael González-Val. I imagine some readers of the blog might find them  useful  interesting.

ps. The AAG was great with some really good thought provoking sessions. I'm still in the Bay area for two more days, visiting the team at Berkeley Urban Planning to talk about transportation and accessibility modelling using Pandana .

Sunday, March 27, 2016

On my way to San Francisco

The blog will be a little less active in the next few days as I will be at the AAG in San Francisco. I will be presenting the second paper of my PhD (details below). Anyway, in case you're in SF next week and want to reach out and grab a  coffee  beer, you can drop me line or a tweet.

SessionMega Event Planning for Sustainable Legacies

Mega-events, transport legacy and the redistribution of employment accessibility
Rafael H M Pereira

A growing number of studies have discussed how mega-event strategies to fast-track urban development in host cities are commonly backed by pro-growth discourses, which rely on the assumption that all local residents equally benefit from the trickle-down effect of economic growth and infrastructure investments. What has received much less attention in the literature, however, is the discussion of transport legacy, and particularly the distributive aspects of who benefits from the new transport infrastructure developments once they have been put in place. This paper discusses the social impact of transport legacies in terms of how such developments affect the transport accessibility to job opportunities of different social groups in host cities and whether local governments mobilize these events to reinforce or redress existing patterns of urban inequalities and segregation. As a case study, we analyze Rio de Janeiro (Brazil), looking particularly at the transformations carried out in the city’s transport system in preparation for the 2014 World Cup and 2016 Olympic Games. We make a before-and-after comparison of Rio’s transport system, calculating employment accessibility changes that have resulted from these new investments between 2013 and 2016 and compare how accessibility gains vary across different social groups and areas of the city.

R Links

  1. Using R to model spatial patterns of urban growth in Africa

  2. Great 'course' on network visualization with R, by Katherine Ognyanova

  3. Building a Schelling segregation model in R, by Ben Davies

  4. Basic mapping and attribute joins in R, by Robin Lovelace

  5. A shiny app to explore the demographics of Texas counties, by Kyle Walker

  6. Nathan Yau compares ggplot2 and R Base Graphics

  7. A Compendium of Clean Graphs in R

  8. I've gathered some code to show how to create Flow maps in R using ggplot2