Mcclean Constant Koku Agbalenyo Optimisation of Grains Buffer Stock Facility Locations in the Upper West Region of Ghana

Abstract

This thesis sets out to optimally locate grains buffer stock warehouses amongst the eleven districts of the Upper West region of Ghana. The research conceptualises the logistical gap between food production and its efficient delivery to households as a location problem. Consequently, it discusses the subject of location analysis and its history, examines commercial versus public sector modeling approaches, catalogues location model typologies, and eventually diagnoses the said problem as a network p-median problem. Subsequently, some exact and heuristic algorithms for the p-median model are demonstrated. The research methodology employs an exact solution approach executed with Premium Solver 2014-R2, a spreadsheet software that runs on the Microsoft Excel platform. Instead of using raw distance measures as proxy for travel cost, the research evens out inequalities in road quality by introducing multipliers that act as incentives or penalties on particular road stretches depending on their nature. Another novelty in here is the unconventional use of a spreadsheet package— rather than traditional combinatorial software—as vehicle for executing location problems. The results are in the form of different solution sets that recommend optimal locations for between one to ten facilities, out of which decision options may be selected depending on available budget. For instance, if a decision is made to open only one buffer stock facility, the solution recommends Nadowli town as the optimal location. Similarly, if it is decided to build two facilities, the optimal sites are Wa and Lambussie; whereas Wa, Jirapa and Tumu should be opted for in case of three warehouses. Bearing in mind that each solution set is unique, and that the cost of building facilities and that of constructing networks are inversely related, it is recommended that long term plans be factored into the choice of any location-network configuration. Anything to the contrary is tantamount to making decisions based on myopic heuristics, which the data analysis proves as being suboptimal. Also, this work raises some pertinent issues about the classification of location models and proposes a new categorisation concept called the location-network hierarchy framework.