We have just finished a new working paper entitled "Random planar graphs and the London street network." The abstract for the paper is below:
"In this paper we analyse the street network of London both in its primary and dual representation. To understand its properties, we consider three idealised models based on a grid, a static random planar graph and a growing random planar graph. Comparing the models and the street network, we ﬁnd that the streets of London form a self-organising system whose growth is characterised by a strict interaction between the metrical and informational space. In particular, a principle of least effort appears to create a balance between the physical and the mental effort required to navigate the city."
The full reference is:
Masucci, A. P., Smith, D., Crooks, A. T. and Batty, M. (2009) Random Planar Graphs and the London Street Network, Centre for Advanced Spatial Analysis (University College London): Working Paper 146, London, England. (pdf)