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The University of Southampton

On track: creating a step-change in 21st century railway track

Published: 1 January 2018
Railway field instrumentation
Field instrumentation to measure sleeper deflection using geophones and digital image correlation.

Key details of this case study:

Summary: Our research is creating a step-change in the engineering, economic and environmental performance of railway track to make it fit for a 21st century railway, by developing new design, construction and maintenance techniques.

Status: Completed

Key staff: Professor William Powrie; Professor John Preston; Professor David Thompson; Dr Antonis Zervos


Explore this case study:

The challenge

For the past 150 years, the majority of the world’s railways – including all UK main lines – have run on ballasted track. This has been considered an optimum solution in terms of construction cost, stiffness and drainage properties, and ease of modification. However, the introduction of faster, heavier and more frequent trains makes its limitations more significant, resulting in higher than expected maintenance costs.

To reduce cost and increase capacity a transformation in track performance, by using retro-fit measures or an alternative system, is essential.

The University of Southampton’s challenge has been to understand the relationship between engineering, economic and environmental performance of railway track, and to provide the science needed to underpin a radical overhaul in techniques for 21st century railway track design, construction and maintenance.

What we did

We simulated the actual stress experienced by the soil below the track during train passage more closely than the current industry standard test, and showed that increasing train axle loads may cause old embankments to fail.

We then carried out multiple rig tests to reproduce and test a section of railway track; triaxial tests to study the mechanical behaviour of scaled-down ballast; and detailed numerical models involving thousands of individual, interacting ballast particles. 

By integrating these results we were able to determine the effect of shoulder geometry, sleeper type, fibre reinforcement and under-sleeper pads on ballast settlement and resilient behaviour, and the stresses within the ballast due to typical traffic loads.

Combining these results with those from critical zone field studies enabled us to understand the extent and likely causes of problems; assess the effectiveness of interventions and component improvements in reducing maintenance needs; and improve numerical modelling techniques.

This research was funded by £3,139,382 EPSRC Programme Grant EP/H044949/1, 1/6/2010

Our impact

This Track21 project is cited as an example of research and development best practice in, and forms the basis of, the UK's Department for Transport Rail Technical Strategy (RTS) to 2040. Similarly, Network Rail's (NR's) Technical Strategy cites Track 21 as an enabler of its infrastructure vision.

Our widely distributed Guide to Track Stiffness (ISBN 9780854329946) is fast becoming the UK’s de facto standard, and we are undertaking further infrastructure work as National Rail's Strategic University Partner.

The results and techniques we developed in Track21 have been used to develop track monitoring equipment for Wessex Rail Alliance, to analyse product performance for Progress Rail UK and to advise London Underground Ltd on novel track forms. Our results have also informed HS2 and our techniques are being used in research for the HS1 track.

The EU Horizon 2020 Shift2Rail call adopted ideas generated by Track21, and we have established overseas partnerships with Railway Technical Research Institutes in Japan and Korea and with Deutsche Bahn and SNCF.

The facilities we used

We used the following facilities within the University - the Railway Testing Facility, the μ-VIS X-ray Imaging Centre and the Geotechnical Lab.

Find out more about the Engineering and Environment Faculty's many world class facilities.

Partners we worked with

We worked closely with external stakeholders: Balfour Beatty Rail, Tata Steel, Network Rail Ltd, Rail Safety and Standards Board (RSSB), Railway Industry Association and URS.

The Track21 research project was an academic collaboration between the universities of Southampton, Birmingham and Nottingham.

Related Publications

Ajayi, O., Le Pen, L., Zervos, A., & Powrie, W. (2017). Scaling relationships for strip fibre reinforced aggregates. Canadian Geotechnical Journal, 54(5), 710-719.

Ajayi, O., Le Pen, L., Zervos, A., & Powrie, W. (2016). A behavioural framework for fibre reinforced gravel. Géotechnique, 1-35. DOI: 10.1680/jgeot.16.P.023

Abadi, T., Le Pen, L., Zervos, A., & Powrie, W. (2016). A review and evaluation of ballast settlement models using results from the Southampton Railway Testing Facility (SRTF). Procedia Engineering, 143, 999-1006. DOI: 10.1016/j.proeng.2016.06.089

Harkness, J., Zervos, A., Le Pen, L., Aingaran, S., & Powrie, W. (2016). Discrete element simulation of railway ballast: modelling cell pressure effects in triaxial tests. Granular Matter, 18(65), 1-13. DOI: 10.1007/s10035-016-0660-y

Abadi, T., Le Pen, L., Zervos, A., & Powrie, W. (2016). Improving the performance of railway track through ballast interventions. Proceedings of the Institution of Mechanical Engineers, Part F: Journal of Rail and Rapid Transit, 1-17. DOI: 10.1177/0954409716671545

Abadi, T., Le Pen, L., Zervos, A., & Powrie, W. (2015). Measuring the area and number of ballast particle contacts at sleeper/ballast and ballast/subgrade interfaces. The International Journal of Railway Technology, 4(2), 45-72. DOI: 10.4203/ijrt.4.2

Ahmed, S., Harkness, J., Le Pen, L., Powrie, W., & Zervos, A. (2015). Numerical modelling of railway ballast at the particle scale. International Journal for Numerical and Analytical Methods in Geomechanics. DOI: 10.1002/nag.2424

Smethurst J A, Briggs K M, Powrie W, Ridley A, Butcher D. J. E. (in review). Mechanical and hydrological impacts of tree removal on a clay fill railway embankment. Submitted to Geotechnique

Le Pen, L., Watson, G. V. R and Powrie, W. et al. (2014) The behaviour of railway level crossings: insights through field monitoring. Transportation Geotechnics (doi:10.1016/j.trgeo.2014.05.002).(In Press).

Le Pen, L., Bhandari, Athma Ram and Powrie, W. (2014) Sleeper end resistance of ballasted railway tracks. Journal of Geotechnical and Geoenvironmental Engineering, 140, (5), 04014004. (doi:10.1061/(ASCE)GT.1943-5606.0001088).

Briggs, K.M., Smethurst, J.A., Powrie, W., O’Brien, A.S. and Butcher, D. (2013) Managing the extent of tree removal from railway earthwork slopes. Ecological Engineering, 61, (Part C), 690-696. (doi:10.1016/j.ecoleng.2012.12.076).

Le Pen, L., Powrie, W., Zervos, A., Ahmed, S. and Aingaran, S. (2013) Dependence of shape on particle size for a crushed rock railway ballast. Granular Matter, 15, (6), 849-861. (doi:10.1007/s10035-013-0437-5).

Bhandari, Athma Ram and Powrie, W. (2013) Strength and deformation characteristics of a locked sand at low effective stresses. Granular Matter, 15, (5), 543-556. (doi:10.1007/s10035-013-0426-8).

Briggs, K.M., Smethurst, J.A., Powrie, W. and O’Brien, A.S. (2013) Wet winter pore pressures in railway embankments. Proceedings of the ICE – Geotechnical Engineering, 166, (GE5), 451-465. (doi:10.1680/geng.11.00106).

Priest, J.A., Powrie, W., Le Pen, L., Mac, Patric and Burstow, Mark (2012) The effect of enhanced curving forces on the behaviour of canted ballasted track. Journal of Rail and Rapid Transit, 227, (3), 229-244. (doi:10.1177/0954409712458623).

Kanagasabai, S., Smethurst, J.A. and Powrie, W. (2011) Three dimensional numerical modelling of discrete piles used to stabilise landslides. Canadian Geotechnical Journal, 48, (9), 1393-1411. (doi:10.1139/t11-046).

Le Pen, L.M. and Powrie, W. (2011) Contribution of base, crib and shoulder ballast to the lateral sliding resistance of railway track: a geotechnical perspective. [in special issue: Rail Research UK: The Universities’ Centre for Rail Systems Research] Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit, 225, (2), 113-128. (doi:10.1177/0954409710397094).

Coelho, B., Holscher, P., Priest, J., Powrie, W. and Barends, F. (2011) An assessment of transition zone performance. Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit, 225, (2), 129-139. (doi:10.1177/09544097JRRT389).

Priest, J.A., Powrie, W., Yang, L.A., Grabe, P.J. and Clayton, C.R.I. (2010) Measurements of transient ground movements below a ballasted railway line. Géotechnique, 60, (9), 667-677. (doi:10.1680/geot.7.00172).

Le Pen, L and Powrie, W. (2010) Contribution of base, crib, and shoulder ballast to the lateral sliding resistance of railway tracl: a geotechnical perspective. Proceedings of the Institution of Mechanical Engineers Part F: Journal of Rail and Rapid Transit, 225, (2), 113-128. (doi:10.1177/0954409710397094).

Priest, J. A. and Powrie, W. (2009) Determination of dynamic track modulus from measurement of track velocity during train passage. Journal of Geotechnical and Geoenvironmental Engineering, 135, (11), 1732-1740. (doi:10.1061/(ASCE)GT.1943-5606.0000130).

Awards received for this research

Mr K Briggs won the Cooling Prize Paper in 2010 with his paper entitled 'Charing Embankment: Climate change impacts on embankment hydrology'.

Dr L Le Pen, Dr D Milne, Professor D Thompson and Professor W Powrie received an Honourable Mention for the Quigley award, for their 2016 article titled "Evaluating railway track support stiffness from trackside measurements in the absence of wheel load data" in the Canadian Geotechnical Journal.

Related media

Railway testing facility
The Southampton Railway Testing Facility, where a section of track can be reproduced and tested.

Improving railway track design

A short video highlighting our research on railtrack improvements

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