Work completed in 2024/25
A strategy for progress at the wheel/rail interface
Review of the curving rules in track design
Optimised wheels for tram-train vehicles
Annual Vehicle/Track System Interface Committee and ADHERE seminar
A PhD into the fundamental science of the wheel/rail interface
Lowering vehicle/track forces through a more advanced understanding of the interface.
To maintain the railway in a safe and efficient way, we need a better understanding of the impact of the wheel/rail interface on all aspects of track and vehicle management. This means improved understanding of the influences of the vehicle on the track and the track on the vehicle. Many factors that affect vehicle behaviour and the forces generated are non-intuitive. Small changes in, for example, wheel or rail profile can have a significant effect on the vehicle’s stability and running characteristics.
V/T SIC developed a strategy focusing on how to control and lower the forces generated between vehicle and track. Lowering forces brings many benefits, including:
reduced deterioration rates and less maintenance
reduced wear rates and longer asset life
less curving resistance and reduced traction energy.
Since the forces acting on the wheel are equal and opposite to those acting on the rail, any reduction in force on one side of the interface will also benefit the opposite side.
Achieving reductions will require engagement with, and support across, the industry. The strategy for the wheel/rail interface aligns with the Rail Technical Strategy, focusing on the opportunities and challenges, and identifying where work should be undertaken. Together, these initiatives will contribute to:
making the railway more reliable for the customers
improving workforce safety with fewer interventions needed on the track
making the infrastructure and vehicles more available
reducing costs.
Download the strategy for the wheel/rail interface from the RSSB website.
To discuss the strategy and how you can help achieve the vision it sets out, contact Professor Mark Burstow, Principal Vehicle Track Dynamics Engineer, Network Rail:
Mark.Burstow@networkrail.co.uk
Looking at the justification for existing curving rules, their impact on passenger comfort, and the case for making a change.
The rules governing the design of circular curves and transitions in track are specified in various railway standards. These define parameters such as cant, cant deficiency (CD), and rate of change of CD (ROCCD) to ensure safe and comfortable operation of rail vehicles.
These standards have remained largely unchanged for many years. In some cases, the requirements may have been based on empirical evidence and under conditions that differ to those now seen on the network. In recent years, there have been several recommendations to review the current requirements for CD and ROCCD.
One of the relevant standards, Railway Group Standard (RGS) GCRT5021 Track System Requirements (Issue 5), was being updated. V/T SIC saw an opportunity to undertake a review of curving rules in this and other standards.
The review was carried out by RSSB and its partner the Institute of Railway Research at the University of Huddersfield. It set out to determine whether these requirements can be optimised, considering the impact of any changes on passenger comfort, safety, and track maintenance.
Researchers compared the existing standards with case studies using vehicle dynamics simulations. They examined the impact of curving rules on derailment risk, wear, and passenger comfort. The findings have provided evidence that will facilitate higher speeds on curves and have a positive overall impact on system performance.
Read the full research findings in the RSSB Research Catalogue (COF-UOH-73).
To discuss the research and its findings, contact Dominic Trueman, Head of Research Implementation, RSSB:
Dominic.Trueman@rssb.co.uk
Encouraging integrated transport through research into vehicles that can run on two different rails.
Tram-train services running between tramways and the mainline railway are a popular solution, integrating urban services with travel between towns and cities. A critical element is the wheel/rail interface, as differences in rail profile and track design require a hybrid wheel for operation over both systems.
Experience from the UK Tram Train Pilot showed that a hybrid wheel alone was not sufficient to ensure safe operation, and both track systems had to be changed. This added both capital and operating costs.
V/T SIC supported research into track and wheelset design for tram-train systems, aiming to mitigate some of these issues. The research produced guidance for future tram-train schemes that will reduce delivery time and costs.
Read the research findings in the RSSB Research Catalogue (COF-HTT-01).
The Institute of Railway Research and RSSB are developing a Tram-Train Good Practice Guide with Network Rail and the Light Rail Safety and Standards Board. The guide will encompass all aspects of tram-train operations. Please get in touch if you would like to get involved in developing it.
Contact David Crosbee, Principal Industrial Fellow, Institute of Railway Research, University of Huddersfield:
D.Crosbee@hud.ac.uk
‘This project has enabled a huge leap forward in our understanding of the complex wheel/rail interface issues of operating tram-trains in Great Britain. The work lays the foundation for saving time and costs in future tram train projects.’
‘I think they are great sessions with almost the perfect balance between industry and academia. And very well organised.’
‘It was a lively and entertaining event yesterday covering a wide range of topics and it all worked like clockwork. Well done to all involved.’
‘A fantastic day that was planned very well. A great opportunity to network. The day provided a good overview of some of the current challenges facing the industry and an excellent overview of some of the brilliant work going on.’
This popular annual event brings the latest thinking to engineers and other rail professionals.
A major part of V/T SIC’s role involves communicating the latest knowledge and understanding of vehicle/track interaction to industry. The committee also wants to hear back on new challenges the industry is facing and how innovations have been received.
Our annual seminar is a vital part of that process. The seminar takes place each spring, jointly with the ADHEsion Research Challenge (ADHERE) team. It offers a unique opportunity to hear from experts, researchers, and innovators about the latest insights and solutions on the vehicle/track interface and wheel/rail adhesion.
The 2025 seminar took place in person at the historic Grade 1 listed Hospitium in York on 5 March. The seminar was attended by 102 delegates and received overwhelmingly positive feedback, with 96% of surveyed delegates rating the seminar as ‘Excellent’ or ‘Good’.
The day started with the latest research findings on damage and wear mechanisms and new management approaches for vehicle/track interface issues. The ADHERE seminar in the afternoon covered new knowledge and techniques for better wheel/rail adhesion.
Presentation topics included:
in-service track monitoring to better predict deterioration to infrastructure
heavy axle weight assessment for underline bridges to inform a future route availability planning tool
lessons learnt from the take-up of variable-rate sanders.
Many discussions were undertaken on the implementation of research. The seminar was also accompanied by several exhibitors with interactive equipment.
On 4 March, an informative site visit was undertaken at Holgate Engineering Works (York) to view Network Rail’s Multi Purpose Vehicle seasonal treatment fleet.
Presentations from the March 5 seminar are available on the SPARK Rail Knowledge Hub.
Plans are underway to hold a further seminar in 2026. In order to not miss out on the next seminar, sign up to the quarterly research email.
Contact Ben Altman, Senior Research Analyst, with any queries:
Ben.Altman@rssb.co.uk
Improving understanding of rough surfaces and how they interact with contaminants.
RSSB and the Engineering and Physical Sciences Research Council co-funded a PhD studentship investigating surface roughness at the wheel/rail interface, how it evolves, and the impact of contamination.
The studentship was run by the Centre for Doctoral Training in Integrated Tribology at the Universities of Sheffield and Leeds. It aimed to improve the understanding of contact mechanics and friction behaviour of rough surface interfaces when third-body layers are present.
The Adhesion Research Group, a V/T SIC sub-group, provided guidance and feedback throughout the PhD project. The researcher carried out both experimental and modelling work with contaminants including grease, water, and leaves.
The findings were used to create a model that could generate accurate predictions for water and leaf layers, but further work is needed to predict outcomes for grease.
Read more about the project in the RSSB Research Catalogue (COF-ITR-04).
Contact Melissa Frewin, Senior Partnership and Research Grant Manager, with any queries:
Melissa.Frewin@rssb.co.uk
