  In this paper we deal with the analysis of the solutions of traffic flow
models at multiple scales, both in the case of a single road and of road
networks. We are especially interested in measuring the distance between
traffic states (as they result from the mathematical modeling) and
investigating whether these distances are somehow preserved passing from the
microscopic to the macroscopic scale. By means of both theoretical and
numerical investigations, we show that, on a single road, the notion of
Wasserstein distance fully catches the human perception of distance
independently of the scale, while in the case of networks it partially loses
its nice properties.
