Very good video that explains the historical reasons for the high density urban cores in European cities as against the low density cores and sprawls in American cities. Despite its skyscrapers, the urban sprawl makes New York only half as dense as Paris!
And this is a fascinating article on jobs accessibility maps, developed by the University of Minnesota's Accessibility Observatory, which chart how far you can travel on a transportation network in different times of the day from different locations in a city and the numbers of jobs within that travel zone. The map is constructed with three different datasets - public transit maps and timings, OpenStreetMap data on pedestrian routes and walking times, and census data on job counts in areas.
The map below captures the change in accessibility to jobs, during the 7-9 AM peak morning commute window, between 2010 and 2013. The dark green areas have access to 100% more jobs in 2013 than 2010. The yellow arrow points to a region where bus frequency was significantly increased along a particular line. The red arrow highlights a corridor with a new BRT line, with major improvements to job access right around a single station.
This is an extremely powerful tool for decision-support on planning public transit routes and urban transport infrastructure. Unfortunately, for cities in developing countries, the challenge is with the availability of good underlying data. In this case, very few cities have information about area-wise jobs data or its changes.
But the emergence of innovative business models that incentivise private entities to collect such data does not look a very unrealistic prospect.