Ballast Degradation Modelling: Case study of Addis Ababa Light Rail Transit
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Date
2025-08
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Addis Ababa University
Abstract
Railway infrastructure should be maintained regularly to improve its performance. This operation requires a large investment and shall be planned well to avoid human and financial resource waste. Various studies found that most of the track geometrical irregularities that seek maintenance are related to the degradation of the underlying ballast. This implies that for planning track geometry maintenance the understanding of ballast degradation mechanism is crucial. In this research, a ballast degradation model that characterizes ballast quality degradation and predicts ballast degradation from different parameters is developed for Addis Ababa Light Rail Transit (AALRT). This paper uses a statistical approach for ballast degradation modeling. Fractal dimensioning of track longitudinal level was applied to determine ballast quality index and to characterize ballast quality degradation. Previously recorded inspection data of track longitudinal profile were collected from Ethiopian Railway Corporation (ERC) and used to develop the model. The irregularities of the vertical track profile are quantified as a ballast quality index. This ballast quality index is used as a basis for developing ballast degradation model. Two ballast regression models were developed for straight and curved sections of AALRT. This degradation model is useful for AALRT infrastructure managers for understanding and predicting ballast quality and it will upgrade the performance of the railway maintenance operation.
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Keywords
Railway ballast, ballast quality index, fractal analysis, ballast degradation model