Periodic Reporting for period 2 - IN2ZONE (The Next Generation of Railway Transition Zones)
Reporting period: 2022-06-01 to 2023-05-31
Transition zones at railway tracks require special attention. When a train moves from an embankment towards a stiff structure such as a bridge, culvert and tunnel there is an abrupt change in support stiffness, which increases dynamic wheel loads and causes increased track stresses. At the same time, a differential settlement between the embankment track and structure starts to occur, generating differential track geometry. Sleepers start to lose support from the underlying layers leading to hanging sleepers due to differential settlement. This causes an unequal load distribution, which accelerates the rate at which tracks deteriorate. Thus, more frequent maintenance is needed to always keep the track geometry at desirable limits. Traditional maintenance techniques, such as tamping, are not applicable in transition zones where there is a sharp change from soft to stiff track sections, such as in the vicinity of bridges. Tamping is not practicable close to the bridges since lifting the track is not feasible. Self-correcting sleepers are therefore suggested in order to minimise the requirement for maintenance. They ensure constant support to the rails to provide a smoother transition.
Heavy railway traffic, high speed train passages and poor substructure conditions can lead to frequent maintenance activities, which causes more frequent line closures. A major source of track maintenance costs are the transition areas, as a high level of maintenance is required here to maintain the desired track geometry, ensuring passenger comfort, avoiding speed restrictions, and avoiding faster degradation of the constructions. The impact of changes in the stiffness of the track-supporting layers along the track should be minimised in transition zones, which should provide smooth train movement.
The IN2ZONE research project developed and tested a prototype next-generation transition zone system that will result in a significant improvement in track support conditions and fewer maintenance interventions. The new approach will integrate the most recent existing transition methods with technological advancements from other industries, especially recent material science discoveries. This multidisciplinary approach looked at improving both the track superstructure and substructure designs, guaranteeing that the overall system stiffness is improved. Advanced automatic irregularity correcting sleepers, synthetic and optimised for transition zones, were designed to extend longevity. The transition zone solution will be able to self-correct minor vertical track geometry anomalies and defects as a result of this.
Heavy railway traffic, high speed train passages and poor substructure conditions can lead to frequent maintenance activities, which causes more frequent line closures. A major source of track maintenance costs are the transition areas, as a high level of maintenance is required here to maintain the desired track geometry, ensuring passenger comfort, avoiding speed restrictions, and avoiding faster degradation of the constructions. The impact of changes in the stiffness of the track-supporting layers along the track should be minimised in transition zones, which should provide smooth train movement.
The IN2ZONE research project developed and tested a prototype next-generation transition zone system that will result in a significant improvement in track support conditions and fewer maintenance interventions. The new approach will integrate the most recent existing transition methods with technological advancements from other industries, especially recent material science discoveries. This multidisciplinary approach looked at improving both the track superstructure and substructure designs, guaranteeing that the overall system stiffness is improved. Advanced automatic irregularity correcting sleepers, synthetic and optimised for transition zones, were designed to extend longevity. The transition zone solution will be able to self-correct minor vertical track geometry anomalies and defects as a result of this.
The IN2ZONE Project successfully tested 3 protype, recycled polymer sleepers: a wedge-shaped, SLS-Wedge and SLS-Granular sleepers. Laboratory tests demonstrated that the sleepers could be successfully deployed and reset in TZs. Furthermore, the successful testing of a condition/field-based monitoring system, which is currently deployed and collecting data at a test site in Budapest, Hungary, continues to provide valuable data for follow on projects.
As a penultimate point, in terms of further exploitation, Lankhrost were recently awarded a contract by Network Rail to assist in the development of the next generation of railway sleepers. This will allow Network Rail to explore various sleeper designs for their bending stiffness, flexibility and temperature resistance against an overall requirement for a greener, reduced CO2 manufacture, one of which could be the SLS designed and tested during IN2ZONE.
Finally, as part of the of project objectives, the anticipated impact of WP3 lead Lankhorst led to some early preliminary conversations with a number of infrastructure organisations and standards bodies to ascertain amendments/additions to any existing SLS standards around TZs. As a result of this, the Czech Railway standards board stated that there is the potential to implement SLS into Czech regulation (MVL 102), although a date has yet TBC. This links into the impact on standards and regulations, stated in IN2ZONE Part B, Section 2, Sub-Section 2.1.2 Table 9.
Additional highlights from the project include:
- IN2ZONE concluded that stiffness-based approaches had high complexity and cost when used in a real-world applications. It also concluded that modular solutions were preferable, and stiffness-based approaches typically involved deep-seated improvement works.
- Furthermore, an important challenge identified at TZs under repeated loading is the development of hanging sleepers, particularly near bridges with ballasted tracks, resulting from the loss of support for the sleepers due to differential settlement. To address this problem and reduce maintenance needs, the project developed novel displacement-based solutions - the use of wedge-shaped sleepers, SLS-Wedge and SLS-Granular, made from recycled polymers. Polymer sleepers’ thermal expansion is reduced when compared to conventional ones and polymeric ones show about 3 times lower emissions than concrete ones.
- When addressing NPV, the average labour costs in the EU provided a positive NPV for scenarios with higher traffic volume (22.5 and 30 MGT per annum). Nevertheless, even with the applied uplift the business case for low traffic volume lines (15 MGT per annum) was weak. This suggests that the greatest potential for SLS sleepers is only high traffic volume lines as on less well-used lines, the cost savings cannot outweigh the higher required investment costs.
As a penultimate point, in terms of further exploitation, Lankhrost were recently awarded a contract by Network Rail to assist in the development of the next generation of railway sleepers. This will allow Network Rail to explore various sleeper designs for their bending stiffness, flexibility and temperature resistance against an overall requirement for a greener, reduced CO2 manufacture, one of which could be the SLS designed and tested during IN2ZONE.
Finally, as part of the of project objectives, the anticipated impact of WP3 lead Lankhorst led to some early preliminary conversations with a number of infrastructure organisations and standards bodies to ascertain amendments/additions to any existing SLS standards around TZs. As a result of this, the Czech Railway standards board stated that there is the potential to implement SLS into Czech regulation (MVL 102), although a date has yet TBC. This links into the impact on standards and regulations, stated in IN2ZONE Part B, Section 2, Sub-Section 2.1.2 Table 9.
Additional highlights from the project include:
- IN2ZONE concluded that stiffness-based approaches had high complexity and cost when used in a real-world applications. It also concluded that modular solutions were preferable, and stiffness-based approaches typically involved deep-seated improvement works.
- Furthermore, an important challenge identified at TZs under repeated loading is the development of hanging sleepers, particularly near bridges with ballasted tracks, resulting from the loss of support for the sleepers due to differential settlement. To address this problem and reduce maintenance needs, the project developed novel displacement-based solutions - the use of wedge-shaped sleepers, SLS-Wedge and SLS-Granular, made from recycled polymers. Polymer sleepers’ thermal expansion is reduced when compared to conventional ones and polymeric ones show about 3 times lower emissions than concrete ones.
- When addressing NPV, the average labour costs in the EU provided a positive NPV for scenarios with higher traffic volume (22.5 and 30 MGT per annum). Nevertheless, even with the applied uplift the business case for low traffic volume lines (15 MGT per annum) was weak. This suggests that the greatest potential for SLS sleepers is only high traffic volume lines as on less well-used lines, the cost savings cannot outweigh the higher required investment costs.
The IN2ZONE research project follows a highly interdisciplinary approach with most up-to-date technological tools. The range of fields varies from sensor engineering to geotechnical engineering, from artificial intelligence to railway engineering. Therefore, the outputs of this project are relevant to many kinds of industrial and research organisations.
Two real scale self-levelling sleepers made of plastic were produced. The sleepers were tested in full-scale laboratory facility and the resilience-based monitoring system developed within WP5 implemented. By the end of the project, the short and long-term behaviour of the self-levelling sleepers (SLS) and the resilience-based monitoring system were investigated numerically and experimentally. The prototype recycled polymer self-levelling sleepers have achieved TRL 5, and the next logical step is the deployment stage, starting with TRL 6, to provide direct evidence of their application and suitability in the field. At this time, at least one EU infrastructure manager has engaged with one of project partners around the deployment and testing in-situ, of recycled, polymer-made sleepers.
In addition to the above, the condition/field-based monitoring system has not only been lab tested, but is currently delivering data from a live transition zone site, providing data for future projects and to demonstrate the systems resilience and compatibility. The next step is deployment across all transition zones.
Two real scale self-levelling sleepers made of plastic were produced. The sleepers were tested in full-scale laboratory facility and the resilience-based monitoring system developed within WP5 implemented. By the end of the project, the short and long-term behaviour of the self-levelling sleepers (SLS) and the resilience-based monitoring system were investigated numerically and experimentally. The prototype recycled polymer self-levelling sleepers have achieved TRL 5, and the next logical step is the deployment stage, starting with TRL 6, to provide direct evidence of their application and suitability in the field. At this time, at least one EU infrastructure manager has engaged with one of project partners around the deployment and testing in-situ, of recycled, polymer-made sleepers.
In addition to the above, the condition/field-based monitoring system has not only been lab tested, but is currently delivering data from a live transition zone site, providing data for future projects and to demonstrate the systems resilience and compatibility. The next step is deployment across all transition zones.