Improving a constructive heuristic for the general routing problem

The general routing problem (GRP) is a fundamental (Formula presented.) -hard vehicle routing problem, first defined by Orloff in 1974. It contains as special cases the Chinese postman problem, the rural postman problem, the graphical TSP, and the Steiner TSP. We examine in detail a known constructive heuristic for the GRP, due to Christofides and others. We show how to speed it up, in both theory and practice, while obtaining solutions that are at least as good. Computational results show that, for large instances, our implementation is faster than the original by several orders of magnitude