Journal of Mechanical Engineering and Transport

In the theory and practice of road haulage there are many different types of transport systems, which differ significantly from each other. Urban freight transport is usually performed by one or more vehicles on pendulum or ring routes, i.e., are a small transport system. In such transport systems there is an uneven operation of vehicles, which is the value of the deviation of production in tons and tonne-kilometers, which occurs daily depending on the influence of many factors. The most significant factors that cause uneven operation of vehicles are the inconsistency of the average technical speed of cars and their downtime under load-unloading. 
Uneven operation of cars significantly affects their implementation of the transportation plan, and thus leads to a decrease in productivity and profits of the trucking company. At the same time, a review of previously performed scientific papers showed that the issues of taking into account the unevenness of cars in operational planning were not given enough attention. 
The article proposes to consider the average technical speed and downtime under load-unloading not as determined, but as random variables, the distribution of which is consistent with the normal law. Accordingly, a mathematical apparatus is proposed, which allows to model the operation of a small transport system taking into account the uneven operation of vehicles. Taking into account the probabilistic nature of these values allows to increase the accuracy of modeling the operation of a small transport system and the possible occurrence of queues for loading or unloading in cargo terminals. Based on the use of this mathematical model, the paper improves the methodology of operational planning of urban freight. The use of the proposed technique will reduce downtime of cars and increase the efficiency of the transport company

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