Browsing by Subject "Railway"

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    Open Access
    Condition assessment methods for prestressed concrete railway sleepers: feasibility for South African applications
    (2025) Lambrechs, Astrid; Beushausen, Hans-Dieter
    Concrete sleepers are a key component of railway systems, with estimates showing between 20 million to 35 million currently installed within the South African railway network. The condition assessment of concrete sleepers in South Africa poses a challenge for two main reasons: the scale at which condition measurements need to be conducted, and the poor access to sleepers within the ballast structure. To assess feasibility of concrete sleeper assessment methods, the quality of technical results was reviewed to ensure the information required for long-term lifecycle needs of concrete sleepers can be produced and that the risk associated with failures of critical defects are mitigated. The work established in the literature review was consolidated through a three-phase methodology to provide results for the assessment. This involved a Failure Mode and Effect Analysis (FMEA) that measured how well each of the methods can detect the failure modes, and then benchmarked the condition assessment methods against similar technology currently in use within the South African network. A test for defect relevance checked that the defects identified in the literature were relevant for South African applications and allowed for further categorisation of criticality. Longitudinal cracking and vertical cracks at the rail seat were found to be the most critical defects required to be detected by concrete sleeper condition assessment methods. Vehicle-mounted ultrasonic echo and vehicle-mounted imagining technology methods both showed good technical results from the FMEA, showing better quality information on sleeper condition than current methods in use. But only the vehicle-mounted imaging scored a residual profile value below the recommended technical threshold, and showed to benchmark cost, lead time and operational factors in line with current methods. Consequently, vehicle-mounted imaging is the most feasible option for concrete sleeper condition assessment for South African applications. Sleeper body abrasion cannot be well detected through any methods reviewed and will require further study of methods before visual inspections of this defect can be improved upon. Failure modes of concrete sleepers due to prestressing steel corrosion were unclear and further testing should be done to define what early-stage cracking displays to accurately predict the end of the useful life of a sleeper.
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    Open Access
    Condition assessment methods for prestressed concrete railway sleepers: feasibility for South African applications
    (2025) Lambrechs, Astrid; Beushausen, Hans-Dieter
    Concrete sleepers are a key component of railway systems, with estimates showing between 20 million to 35 million currently installed within the South African railway network. The condition assessment of concrete sleepers in South Africa poses a challenge for two main reasons: the scale at which condition measurements need to be conducted, and the poor access to sleepers within the ballast structure. To assess feasibility of concrete sleeper assessment methods, the quality of technical results was reviewed to ensure the information required for long-term lifecycle needs of concrete sleepers can be produced and that the risk associated with failures of critical defects are mitigated. The work established in the literature review was consolidated through a three-phase methodology to provide results for the assessment. This involved a Failure Mode and Effect Analysis (FMEA) that measured how well each of the methods can detect the failure modes, and then benchmarked the condition assessment methods against similar technology currently in use within the South African network. A test for defect relevance checked that the defects identified in the literature were relevant for South African applications and allowed for further categorisation of criticality. Longitudinal cracking and vertical cracks at the rail seat were found to be the most critical defects required to be detected by concrete sleeper condition assessment methods. Vehicle-mounted ultrasonic echo and vehicle-mounted imagining technology methods both showed good technical results from the FMEA, showing better quality information on sleeper condition than current methods in use. But only the vehicle-mounted imaging scored a residual profile value below the recommended technical threshold, and showed to benchmark cost, lead time and operational factors in line with current methods. Consequently, vehicle-mounted imaging is the most feasible option for concrete sleeper condition assessment for South African applications. Sleeper body abrasion cannot be well detected through any methods reviewed and will require further study of methods before visual inspections of this defect can be improved upon. Failure modes of concrete sleepers due to prestressing steel corrosion were unclear and further testing should be done to define what early-stage cracking displays to accurately predict the end of the useful life of a sleeper.
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    Open Access
    [Re]connected and on track integrating the Nelson Mandela Bay commuter rail line with the Swartkops area through a re-imagined future
    (2025) Hill, Robert; Ewing, Kathryn; Crooijmans-Lemmer, Hedwig; Truter, Georgina Jani
    South Africa remains shaped largely by its apartheid past and its associated Modernist planning practices. This has left South African cities as fragmented, disconnected, and inequitable spaces, especially for those who still directly feel the effects of exclusionary planning practices.The commuter rail line in Nelson Mandela Bay, running between Gqeberha (formerly Port Elizabeth) and Kariega (formerly Uitenhage) is an example of a public transport system that has failed to adapt to changes in where and how people live and move. As such, it is characterised by low frequency, low usage, inaccessible and outdated stations, and antiquated infrastructure. The line is the least used of all the Metrorail systems in South Africa by a large margin, and as such there has been a reluctance to invest into improving the existing system. Many of the stations are far removed from where the majority of the people live, particularly in the township areas of Gqeberha - the most densely populated neighbourhoods in the metro.The line itself runs, for a large portion of its length, along the Swartkops Estuary and river, a partially protected conservation area. Various plans to improve the line have been proposed, but numerous factors have led to these not being implemented. A long-term plan has involved the so-called Motherwell Loop, which aims to connect the far-removed township of Motherwell into the existing rail system. This project looks at how the line can be reimagined: not just as an infrastructural project - but as an integrated system that adds to the urban life in the metro, and creates a spatially just urban environment. This is done specifically through re-imagining the railway line by rerouting the commuter line to include the township of Motherwell, and by re-imagining the rest of the line as a corridor that connects people to the Swartkops natural system, to allow for social justice in terms of access to the city and to the natural environment.The focus area in this re-imagining becomes the Swartkops area, and the corridor linking the Njoli Square node to the Swartkops Station, village, and estuary, running through a re-imagined urban campus housing the Nelson Mandela University Ocean Sciences Campus. Currently the Swartkops Station sits isolated from its main users - people from the Kwazakhele township - and sits in an area of intense environmental degradation. This corridor of activity becomes defined by the thresholds it crosses in, and how these thresholds or edges are defined: the township to natural edge, the commerical corridor to residential edge, and the estuary to activity edge.Through these interventions, the village of Swartkops becomes a focal node in the urban fabric of Nelson Mandela Bay, and is integrated with its adjacent neighbourhoods, though a mobility corridor that links all these elements together through the creation of a safe, walkable and meaningful space, in the pursuit of a more spatially just urban landscape