Figure 1

Travel-Time Expenditure distributions. (Left) Travel-Time Expenditure (TTE) distribution for the city of Naples (≈1 million inhabitants). The empirical probability density \(p(T)\) (dots) is correctly interpolated by the curve (6) (solid line) with \(\alpha= 0.61\mbox{ h}\), \(\beta= 1.11\mbox{ h}\) and \(R^{2} = 0.99\). The dashed line, shown as a guide to the eye, represents an exponential decay with a characteristic time β. (Right) TTE distribution for the city of Grosseto (\({\approx} 80{,}000\) inhabitants). The interpolation with the curve (6) is successful also for smaller cities like Grosseto: in this case the parameter values are \(\alpha= 0.38\mbox{ h}\), \(\beta= 0.83\mbox{ h}\) and \(R^{2} = 0.99\).