Case study on the rehabilitation of an old African heavy haul freight line

Abstract

In many countries, old railways have to be renewed in order to fulfil modern quality requirements, either related to higher travel speeds, to greater axle loads or to increased capacity. Preferably, such renewal works should be carried out in an economical and environmental sustainable process, taking into account the existing materials and the in situ conditions of the structure. This paper presents studies carried out in order to establish track structural configurations for the rehabilitation of a long old international railway line in Africa that is expected to accommodate heavy freight traffic in the near future. The visual inspection performed throughout the line, the analysis of the characteristics of the existing superstructure and the substructure survey made it possible to identify the thickness of the layers, soils characteristics and to evaluate stiffness of the track bed. An experimental study was carried out in a deactivated rail stretch in order to assess the feasibility of different track structural configurations, in what regarded costs and construction processes. Results of Ground Penetrating Radar (GPR) surveys, Plate Load Tests (PLT) and Falling Weight Deflectometer (FWD) tests performed on the experimental site are also presented herein. A numerical modelling analysis of the different structural configurations that were tested in the experimental site is also presented. Stress and deformation results are analysed and compared