Tour Improvement Algorithms the tour construction heuristic is a greedy approach. The part of the tour, which is already built, remains unchanged during the tour construction process. No attempt is made to change or undo part of the tour that has been built. This is in contrast to the tour improvement heuristic which changes the configuration of the tour during the iterative improvement process until a short tour is found. A simple example of this type of algorithm is the: 2-Opt Algorithm This algorithm starts from either a random tour or from the tour that resulted from the nearest neighbor heuristic. In this method replace 2 links of the tour with 2 other links in such a way that the new tour length is shorter. Continue in this way until no more improvements are possible.