The Vehicle Routing Problem (VRP) is a NP
complete problem and is also a hot topic in the operational
research. But traditional methods might suffer from slow
convergence and the curse of large sizes, heuristics-based
swarm intelligence can be an efficient alternative. Particle
swarm optimization (PSO) is known to effectively solve
engineering optimization problems. In this paper, the PSO in
solving VRP is comprehensive surveyed from two basic
aspects: the improved PSO algorithms and the particle
encoding method. For each application, technical details that
are required are all discussed. Finally, a summary is given
together with suggestions for future research.