The previously developed optimization model for determining the required number of vehicles as part of the harvest transportation complex during grain crop harvesting for the conditions of grain farming in Poltava region has been applied. A computational methodology was developed to determine the design parameters depending on the farm conditions included in the expression for the target function of the optimization model constructed, namely, average number of arrival rate per time and waiting time in queue (excludes service time) for each individual customer. Using the queueing theory methods, a ratio of the number of harvesting and transport equipment in the harvest transportation complex composition was found, which provides the minimum total costs (corresponding to the target function of the previously proposed model), which are due to the downtime of combine harvesters and the cost of vehicle maintaining. It has been established that with the increase in the vehicle number, the total costs of downtime of combine harvesters and vehicles decrease at first and then increase.