As it is intended to concentrate on VRPTW, literature
survey will focus on VRPTW and its solution methods. In
VRPTW each customer has an associated, fixed time
interval during which service must be provided. A lot of
work has been done in the field of VRPTW [2, 3]. As
VRPTW is NP hard, techniques like exact optimization
and heuristics approaches have been used for solving
VRPTW. In [19], author categorized vehicle routing
methods into three generations. The first generation wassimple heuristics, based on local search and sweep that
terminates once local optima has been found. Second
generation, mathematical programming based heuristic,
were near-optimization algorithms that are very different
from normal heuristics generating superior results than
prior generation. Third generation that is currently at the
center of research is the meta heuristics. In the following
section third generation methods are briefly introduced.
Meta heuristics can be broadly classified into three
categories: (i) local search, (ii) population search, and (iii)
learning mechanisms.