Wednesday, January 12, 2011
David Matthew Levinson (Minnesota) and Bhanu Yerra (Minnesota) have posted How Land Use Shapes the Evolution of Road Networks. The abstract:
The present research develops a model to treat the organization, growth, and contraction of network elements. The components of the model include travel demand, revenue, cost, and investment. Revenue earned by links in excess of maintenance costs is invested on the link until all revenue is consumed. After upgrading (or downgrading) each link in the network, the time period is incremented and the whole process is repeated until an equilibrium is reached or it is clear that it cannot be achieved. The model is tested with three alternative land use patterns: uniform, random, and bell-shaped, to test the effects of land use on resulting network patterns. It is also tested with alternative values of the trip distribution friction factor. It is found that similar, but not identical, equilibrium hierarchical networks result in all cases, with the bell-shaped land use network, with a CBD, having higher level roads concentrated in a belt around the CBD, while the other networks are less concentrated. The results suggest that networks are capable of self-organizing, and that the nature of that organization depends on land use and traveler preferences.