Efficiency of heuristic algorithms in solving waste collection vehicle routing problem: a case study

This paper investigated the efficiency of six heuristic algorithms from prior studies in the attempt to solve issues related to waste collection, namely: (i) Nearest Greedy (NG), (ii) Further from Depot (FFD), (iii) Different Initial Customer (DIC), (iv) Savings Approach, (v) Sweep Algorithm, and (vi) Different Initial Customer based on Sweep Algorithm. In fact, these heuristics have been employed to solve several routing problems in past studies, but the performance of each heuristic has never been compared. Hence, this paper looked into the efficiency of these heuristics by testing them on a real case study of waste collection problem in a district located at the north of Peninsular Malaysia. Several solutions obtained from these heuristics were compared with solutions implemented by the waste collection company, especially in terms of the total distance travelled. As a result, the computational results exhibited that DIC generated the best solutions, when compared to other heuristics, with a 12% reduction of the total travel distance

Proposta de metodologia para o estudo da localização de instalações destinadas ao parqueamento de viaturas de transporte de mercadorias alimentares

O transporte rodoviário de mercadorias, embora essencial, gera custos elevados às organizações, criando a necessidade de subcontratação de empresas transportadoras. Contudo, estas também enfrentam desafios logísticos, nomeadamente no planeamento da localização de instalações. O objetivo da dissertação consiste em desenvolver uma metodologia para estudar a localização de instalações destinadas ao parqueamento de viaturas de transporte de mercadorias alimentares. A metodologia propõe a aplicação de problemas de programação linear, desenvolvidos através de alterações realizadas à formulação clássica do problema de localização simples de instalações, e integra os critérios de decisão minimax da oportunidade perdida e Hurwicz na análise da incerteza na procura. Adicionalmente, aplica a análise ABC no processo de tratamento de dados e a análise de sensibilidade dos problemas de programação linear. Devido à localização pouco estratégica da sua sede, a Transportes Paulo Duarte Lda. revelou sofrer de custos elevados resultantes de deslocações realizadas pelas viaturas vazias dos serviços de transporte de líquidos alimentares nacional (Serviço_LAS) e frigorífico internacional (Serviço_FI), tendo, por isso, constituído o objeto do presente estudo de caso. Verificou-se que a decisão que minimiza os custos totais consiste em gerir, em conjunto, as instalações já existentes na Azambuja e em Torres Vedras. Considerando os custos de deslocação dos motoristas, estima-se um custo total médio entre cenários de 348 388 € para o Serviço_LAS e 449 766 € para o Serviço_FI, aproximadamente. A metodologia proposta permitiu responder ao problema apresentado pela Transportes Paulo Duarte Ld.Road freight transport, although essential, generates high costs for organizations, creating the need for outsourcing transport companies. However, they also face logistical challenges, namely in plant location planning. The goal of the dissertation is to develop a methodology for the study of the location of facilities for the parking of food transport vehicles. The methodology proposes the application of linear programming problems, developed through changes made to the classic formulation of the uncapacitated facility location problem, and integrates the decision criteria minimax regret and Hurwicz in the analysis of demand uncertainty. In addition, it applies ABC analysis to the data processing process and analyzes the sensitivity of linear programming problems. Due to the lack of strategic location of its headquarters, Transportes Paulo Duarte Lda. revealed to suffer from high costs associated with trips made by the empty vehicles of the national food liquid transport service (Serviço_LAS) and international refrigerator service (Serviço_FI), having, therefore, constituted the object of the case study. It was found that the decision that minimizes total costs is to jointly manage the facilities that already exist in Azambuja and Torres Vedras. Considering the travel costs of the drivers, it is estimated an average total cost between scenarios of 348 388 € for the Service_LAS and 449 766 € for the Service_FI, approximately. The proposed methodology allowed to solve the problem presented by Transportes Paulo Duarte Lda