# On the Perturbation of Self-Organized Urban Street Networks

## TL;DR

This paper models urban street networks using principles from physics, showing how external influences can perturb their structure and potentially indicate social disengagement.

## Contribution

It extends a physics-based model of self-organized urban street networks by incorporating external surprisal drift, enabling analysis of perturbations and social implications.

## Key findings

- The model recovers scale-free distributions of roads and junctions.
- External surprisal drift affects the network's statistical properties.
- The external drift may serve as an indicator of city-dwellers' disengagement.

## Abstract

We investigate urban street networks as a whole within the frameworks of information physics and statistical physics. Urban street networks are envisaged as evolving social systems subject to a Boltzmann-mesoscopic entropy conservation. For self-organized urban street networks, our paradigm has already allowed us to recover the effectively observed scale-free distribution of roads and to foresee the distribution of junctions. The entropy conservation is interpreted as the conservation of the surprisal of the city-dwellers for their urban street network. In view to extend our investigations to other urban street networks, we consider to perturb our model for self-organized urban street networks by adding an external surprisal drift. We obtain the statistics for slightly drifted self-organized urban street networks. Besides being practical and manageable, this statistics separates the macroscopic evolution scale parameter from the mesoscopic social parameters. This opens the door to observational investigations on the universality of the evolution scale parameter. Ultimately, we argue that the strength of the external surprisal drift might be an indicator for the disengagement of the city-dwellers for their city.