Metric total segment length is defined as the metric distance from the mid-point of origin segment to that of destination segment along a smallest metric distance path.
Metric total segment length
Hillier , B. & Iida, S. (2005), Network and psychological effects in urban movement, In: A.G. Cohn and D.M. Mark (Eds.): COSIT 2005, LNCS 3693, pp. 475-490.