Earthworks risk assessment on a heritage railway

The UK is home to a substantial number of heritage and tourist railways, which make a significant contribution to their local economies. They are mostly constructed on the routes of closed lines, and include large numbers of earthworks of uncertain construction and unknown strength. Recently, there have been earthwork collapses, most notably on the Gloucester and Warwickshire Railway during 2010 and 2011. The Office of Rail Regulation has also noted a number of safety incidents on heritage railways, all attributable to management failures. This paper describes an analysis of the Victorian earthworks on the Bo'ness and Kinneil Railway, a 8 km-long heritage railway in central Scotland. The analysis and risk prioritisation method used by Network Rail was found to be unsuitable for direct application to heritage railways, owing to the different operating context. A new system was therefore developed, removing some risk factors from the Network Rail approach, adding others, and modifying further ones. The new system was successfully applied, and the Bo'ness and Kinneil Railway earthworks were found to be generally stable and safe

Improved performance of geosynthetics enhanced ballast: laboratory and numerical studies

Ballasted rail tracks form one of the most important worldwide transportation modes in terms of traffic tonnage, serving the needs of bulk freight and passenger movement. High impact and cyclic loads can cause a significant deformation leading to poor track geometry. In order to mitigate these problems, the concept of the inclusion of geosynthetics in rail tracks is introduced. This paper presents the current state-of-the-art knowledge of rail track geomechanics, including results obtained from laboratory testing, field investigations and numerical modelling to study the load-deformation behaviour of ballast improved by geosynthetics. The shear stress-strain and deformation behaviour of geosynthetic-reinforced ballast are investigated in the laboratory using a large-scale direct shear test device, a track process simulation apparatus and a drop-weight impact testing equipment. Computational modelling using the discrete-element method is employed to simulate geosynthetic-reinforced ballasted tracks, capturing the discrete nature of ballast aggregates when subjected to various types of loading and boundary conditions. Discreteelement modelling is also used to conduct micromechanical analysis at the interface between ballast and geogrid, providing further insight into the behaviour of ballast subjected to cyclic loadings. These results provide promising approaches to incorporate into existing track design routines catering for future high-speed trains and heavier heavy hauls