A MULTI-OBJECTIVE TOUR ROUTING PROBLEM CONSIDERING THE TIME WINDOW AND TOURIST UTILITY

This paper optimizes a tour route for tourists in groups considering time windows and tourist fatigue. It is based on points of interests, which are
grouped in clusters and is a branch of an orienteering problem, known as a Tourist Trip Design Problem with clustered points of interests. There are a variety of transportation modes for trips, in which all the tourists in a group can choose one respecting some constraints, such as time, distance, and possibility of using a specific vehicle. Each point of view has starting and finishing service times for tourists. Therefore, each point of interest can be visited only in a special time window. In such problems, human health and energy should be noticed so that tourists can enjoy most of the tour and the total utility is increased. One of important factors in human health and energy is fatigue. To apply the factor into the problem and express it implicitly, points of interests are grouped into three clusters based on activities that tourists do in each kind of point of views: tourist attractions, shopping malls, and resting places. In each route, tourists must visit at least one place of each cluster so that fatigue can be relieved. A mixed-integer linear programming model with two objective functions is proposed. The model is verified and assessed through five numerical examples that is designed for a hypothetical tourist area. The example is solved by GAMS software using the CPLEX solver. Also, the sensitivity analysis based on each objective function separately is performed on some of the parameters, such as visiting costs and time windows. Therefore, both tourists and managers with certain points of interests can plan and change them to decrease the cost and increase the utility and visits.