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.
