Stages of operating vehicles with respect to operational efficiency using city buses as an example

In large urban agglomerations, public transport faces a new challenge, which is the progressive increase in the number of vehicles used and the resulting restrictions on traffic flow and driving safety as well as noise and environmental pollution. Research conducted in many countries has proved that public transport should absolutely dominate in passenger urban traffic due to environmental and transport efficiency [6, 10, 18]. An important problem of the public collective transport is the reliability of transport means. Low level of reliability of buses worsens the punctuality of the system and decreases passenger confidence, as well as increases transport costs and reduces the effective use of the fleet. Therefore, many transport companies pay a lot of attention to the selection of high-quality transport means [15]. It means striving to balance two requirements: ensuring maximum reliability at an acceptable level of investment and operating costs [3, 5, 7, 8, 16]. For this reason, transport enterprises use systems for monitoring the risk of wear defect and diagnosing the change in the residual value of the vehicles used [17]. This is an important problem from the point of view of ensuring the continuity of the transport system in the city. Another important problem in the process of vehicle operation is the issue of time limit (end) of use, after which the vehicle should be taken out of service (replaced or disposed of) [1, 14]. The paper [12] presents results of technical readiness tests of the city buses as a function of time of use. It has been demonstrated that technical readiness during the warranty and post-warranty periods may vary significantly depending on the bus make. A more comprehensive picture of the vehicle’s operational characteristics can be obtained after considering the costs of repairs related to the physical wear of components and parts [11, 17]. It is then possible to assess the operational efficiency of the vehicle depending on the time of use or the mileage. Operational efficiency is one of the most important characteristics of the operational quality of the vehicle and may be a criterion for assessing its operational usefulness [2, 13, 14]. This article presents the author’s model for the assessment of operational efficiency and its use to determine the rational time of use (service life) of the buses. This model takes into account the indicators of technical readiness and reliability of vehicles as well as related costs of repairs and downtime. The model is the basis for the new division of time of use for a period of full operational usefulness and limited operational usefulness of buses. The model has been verified based on the bus tests during the 6 years of operation using the city of Lublin as an example. NiewczAs A, RymARz J, DebickA e. stages of operating vehicles with respect to operational efficiency using city buses as an example. eksploatacja i Niezawodnosc – maintenance and Reliability 2019; 21 (1): 21–27, http://dx.doi.org/10.17531/ein.2019.1.3.