平均效应指随半径增加，线段数目也增加，线段的长短差别因素变得不重要，由此线段的总长度近似于线段数量。
平均效应
Sources
Hillier, B., Turner, A., Yang, T., Park, H-T. (2007, 2010) Metric and topo-geometric properties of urban street networks: some convergencies, divergencies and new results. The Journal of Space Syntax, V(1) 2, 258-279. pp.263