Figure 12

Percentage of edges and shipping length by edge type for various values of distance threshold α, the detour factor threshold (“detour”), as well as using the entire set of minimum-route paths (“all”). As in Fig. 8, numbers in parentheses correspond to length-to-edge percentage ratios. Results are similar for paths between all peripheral ports and paths between peripheral ports that include at least one core edge, and results are broadly similar across threshold values. Looking at all of the paths between peripheral ports, when only the minimum shipping distance path is kept (\(\alpha =1.0\)), core edges account for about 17.1% of the total length, but after adding a small number of paths close to the minimum distance (\(\alpha =1.05\)) the involvement of the core increases to 26.8%. As α increases, the percentage of core edges varies between 23.6% and 28.1%, while the detour threshold percentage is 20.3%. Turning to the paths between peripheral ports that pass through the core, at \(\alpha =1.0\) core edges account for about 28.5% of the total length, but at \(\alpha =1.05\) the involvement of the core increases to 35.9%. As α grows and fewer paths are filtered, the length percentage accounted for by the core decreases to 26.1% when all minimum-route paths are included, and is 25.3% using detour factor filtering