Chris Bruntlett points out to this great drawing by Karl Jilg depicting 'the sad state of walking in our cities'. It's a nice way to illustrate how much public space is dedicated to cars in our cities and its health risk implications.
[image credit: Karl Jilg/Swedish Road Administration]
It is a well known and old stylized fact that cars occupy a disproportional amount of road space. Artistic expressions a aside and despite the effort of a few good researchers, no one really knows how much road space we actually dedicate to cars compared to other transport modes. This is not a trivial question to answer. There are many variables involved (including vehicle occupancy rates, vehicle speeds, the amount of road and parking spaces, fleet composition, etc), these variables change drastically across different parts of the city and different times of the day and such data is hardly available.
In the 'time of big data' with very profound and rapid changes in data collection, there are huge opportunities to advance this research agenda using computational modelling and I've been really tempted to work on this topic during my PhD. Would someone like join me? ;)