TITLE:
A Bi-Objective Study of the Weekly Stability of Household Waste Collection in the City of Conakry, with the Number of Single-Frequency Collection Points Is Greater than That of Double-Collection Points
AUTHORS:
Ousmane Toure, Mohamed Dinah Bangoura, Maurice Leno, Castro Gbêmêmali Hounmenou, Baba Mansare, Binko Mamady Toure, Abdoulaye Toure
KEYWORDS:
Waste Collection, Conakry, Optimization, VRP, CARP, Waste Management
JOURNAL NAME:
Journal of Applied Mathematics and Physics,
Vol.14 No.1,
January
22,
2026
ABSTRACT: This article examines the weekly optimization of household waste collection in Conakry, Guinea. Faced with increasing waste volumes, the study proposes an organization into two sets of routes: at the beginning (
S
deb
) and end of the week (
S
fin
). The objective is twofold: to minimize the total cost (distance traveled) and to maximize stability between these two sets, i.e., to reduce their differences. The methodology is based on a mathematical model of the Vehicle Routing Problem with Time Windows (VRPTW) type, adapted to account for collection frequency (once or twice a week). The central hypothesis is that the number of single-frequency collection points is greater than that of double-collection points. For this scenario, two heuristic methods are designed and tested on modified Solomon instances. The results indicate a trade-off between the objectives. Method 1, which first builds tours for the
Z
c
2
nodes and then inserts the
Z
c
1
nodes, generally yields better results in terms of cost reduction. Method 2, which iteratively completes each existing tour, favors better overall stability between the beginning- and end-of-week routes. Thus, the choice of method depends on the priority set by the decision-maker: cost minimization or pursuit of operational stability.