Fig. 4: Density of main roads and REZs and the distribution of REZ extent per kilometre of road.
From: Global expansion of the ecological impact of extra-urban road traffic
a, Extra-urban road densities plotted against the density of REZs caused by moderate to very high traffic. The x axis has a logarithmic scale. b, Frequency distribution of REZ extent per kilometre of road (an indicator of road use intensity) binned into nine classes for moderate, high and very high road traffic impact. Raster cells containing a road but no REZ are in the class labelled 0. For these plots, only 5 km × 5 km raster cells containing extra-urban main roads were considered (n = 1,242,345).
