Queue model of technical readiness of large car fleet

Introduction. A making decisions about the volume of vehicle repairs after breakdowns is based on the minimum cost of repairs. However, this can lead to a decrease in the technical readiness of the enterprise as a whole, non-fulfillment of applications for transportation and economic damage. To calculate the required amount of repair work, leading to a sufficient increase in the technical readiness of the vehicle, a model of the enterprise’s activity is needed, which allows calculating the consequences of a particular volume of repair work with respect to the fulfillment of transportation requests. Aim. A development of a stochastic queue model of the activity of a truck enterprise, taking into account a decrease in the technical readiness of vehicles during operation. Materials and methods. The analysis of the structure of the costs of operating vehicles, including repair costs. The structure of the simulation model, including the full life cycle of transportation and repair work, is substantiated. The assumptions inherent in the working conditions of a large motor transport enterprise are adopted. The model is implemented in the GPSS language. The technical availability of an individual vehicle is approximated by a piecewise linear function. The information on the modeling procedure is given. Results. The adequacy of the simulation results was checked when changing factors leading to obvious consequences: speed of vehicles, number of vehicles in the fleet, time of repair work. Consistency of results is shown. The possibility of increasing the implementation of the system of applications for transportation through more comprehensive repair work has been investigated. An asymptotic dependence of fleet availability as a whole on the degree of recovery of vehicles as a result of repairs was obtained. Conclusion. The model is developed can be used as a module of a decision support system for managing a motor transport enterprise.