Instances for the Shared Customer Collaboration Vehicle Routing Problem Version 2 (SCC-VRP)

This document describes the three groups of instances, S3 and S3E, used in the Shared Customer Collaboration Vehicle Routing Problem (SCC-VRP). 
Each group follows different generation criteria and is based on prior work from the literature. 

Note on S3 instances. Unlike S3E, whose costs are Euclidean and therefore metric by construction, the arc costs in the S3 instances are generated at random and do not satisfy the triangle inequality. To obtain well-defined routing costs, the cost between each pair of locations must be taken as the length of the shortest path between them rather than the raw arc cost, i.e. the cost matrix must be replaced by its metric closure before optimization. Because routing in the SCC-VRP is carrier-specific, i.e. each carrier r may only traverse arcs among its own customers and its depot, the shortest paths must be computed within each carrier's subgraph. For a shared customer,
which may be served by any of the carriers requesting its goods, the applicable shortest-path cost depends on the carrier to which it is assigned in a given solution; the metric closure must therefore be computed per carrier and not on a single global graph.