No abstract

In the track quality analysis, numerical values representing the relative condition of track geometry called track quality indices (TQIs) are calculated along a specific track segment. Segments are defined as linear track geometry datasets with the homogeneous characteristics of factors affecting geometry degradation. The 200m-long analytical segment is used most often on inter-city conventional and high-speed rail networks. However, in the case of the small urban rail networks, the homogeneity of track-geometry degradation influential factors is very low. This segment length is usually too long for efficient track maintenance or reconstruction with minimal disruption of the urban traffic. This paper explores the effect of reducing the analytical segment length in the condition assessment of the tram network in the City of Osijek, Croatia. The research had two main objectives: (1) to assess the narrow-gauge tram-track geometry quality through the application of the established synthesized TQIs, and (2) to analyze how a change in the analytical segment length affects this assessment. Two synthesized track quality indices—one based on a weighted value and the other on a standard deviation of measured track geometry parameters—were calculated for the 27.5 km of tracks on consecutive 200-, 100-, 50-, and 25 m long analytical segments. The comparative analysis of the TQIs’ calculation results showed that the reduction in the segment length increased the resolution of the track quality analysis in both cases, while the index based on a weighted value of geometry deviations proved less sensitive to this reduction. These results contribute to further segmentation process establishment and TQIs implementation on tram infrastructure.

Urban transport plays a key role in the sustainable development of large cities. Urban railway systems, as eco-friendly mass transport systems, are becoming the basis of urban traffic development. Maintaining a high-quality service with continuously increasing traffic demand places an additional burden on public transport operators. Track geometry control has a major impact on availability and maintenance costs of public transport. Good management of rail infrastructure involves continuous monitoring of track geometry (track gauge, cant, twist, horizontal and vertical irregularities) where surveying should be done up to several times a year. Measuring of track geometry in chosen track cross-sections can be done automatically with relatively expensive equipment, or manually which is cheaper but takes longer. Therefore, the question arose as to whether it is possible on small urban railway networks to reduce monitoring scope by increasing of sampling distance, and if so, what should be recommended sampling distance. This paper presents, on the example of the City of Osijek tramway system, how changes in sampling distance effects on track gauge parameter. The results of the conducted analyses are presented and discussed. The recommendations on track gauge monitoring scope optimization on small urban networks are made.

The stop dwell time can be modelled by using the volumes of boarders and alighters, and it is a common conclusion that the use of additional information on the number and width of doors, number of seats, and number of through standees in model creation improves its estimation of stop dwell time. However, such an approach demands detailed knowledge and/or assumptions on passenger distribution both inside the vehicle and on the stop platform, which makes the model creation and its application more challenging. The research presented in this paper is focused on the passenger input data requirements for the creation of tram stop dwell time prediction models. It is based on passenger and tram dwell time data collected at an island tram stop in Zagreb. The data acquisition included the field recording of the trams in operation during five working days, laboratory processing of 70 hours of collected video data, and creation of a synthesized database of observed and measured data. Three different multiple linear regression models for tram dwell time prediction were created, with the following independent variables: (1) the volume of boarders and alighters and a type of passenger flow transiting through the busiest tram doors, (2) the volume of boarders and alighters transiting through the busiest tram doors, and (3) the total volume of boarders and alighters per tram. The cross-validation of the model showed that passenger input data simplification has a minor effect on the model’s goodness of fit, and a mild effect on it’s accuracy and precision, which could be adequately addressed by the application of a larger operating margin.

U ovome radu prikazan je, na primjeru tramvajskog sustava Grada Osijeka, utjecaj degradacije kvalitete geometrije tramvajskog kolosijeka na brzinu putovanja tramvajskog vozila, tj. na promjenu prometne ponude te posljedično na prometnu potražnju. Promjena kvalitete geometrije tramvajskog kolosijeka tijekom uporabe ima izravan utjecaj na smanjenje brzine kretanja tramvajskog vozila, tj. na povećanje trajanja putovanja tramvajem. Posljedično, promjena kvalitete geometrije tramvajskog kolosijeka utječe na promjenu razine usluge, te konačno na promjenu broja korisnika tramvajskog prometnog sustava. Planiranjem i pravovremenim održavanjem tramvajskog kolosijeka moguće je smanjiti negativne utjecaje promjene kvalitete geometrije tramvajskog kolosijeka na učinke tramvajskog prometnog sustava.