Figure 6

Evolution of the exponents \(\alpha_{1}\) of daily directed and undirected freight highway transportation networks. (a) Scatter data of \(F_{ij}\) with respect to \(P_{i}P_{j}/d_{ij}^{2}\) for the directed network. (b) Binning data of \(F_{ij}\) with respect to \(P_{i}P_{j}/d_{ij}^{2}\) for the directed network. (c) Scatter data of \(W_{ij}\) with respect to \(P_{i}P_{j}/d_{ij}^{2}\) for the undirected network. (d) Binning data of \(W_{ij}\) with respect to \(P_{i}P_{j}/d_{ij}^{2}\) for the undirected network