Tuesday, April 26, 2016

Traffic Inducing Traffic

Sunday, April 24, 2016

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 create 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 .