This article first appeared in the Railway-News Magazine Issue 3 2023.
Since the costly issue of mud pumping was identified by the rail industry, decades of research have gone into developing solutions, which have evolved over time.
Problem areas of ballast contamination in trackbeds cause a real headache for rail operators and contractors alike. But solving the issue often has a considerable impact on day-to-day operations and budgets, due to demanding track possession times and frequent maintenance intervals.
Re-ballasting has often been adopted as a solution. However, this is a short-term answer and over time, the problem returns – again and again. The cost implication of regular, repeated maintenance is significant but can be avoided by employing a specialist solution. There are three targeted methods that have been used over the years to tackle mud pumping:
Traditionally, mud-pumping was treated with the installation of a 300mm thick sand blanket. While this proved very effective at preventing the migration of fines, the installation of a sand blanket requires significant excavation – and consequently a large volume of material needing to be imported and exported. This makes for a slow and expensive installation – a challenging exercise to complete within a given possession window.
As geotextiles were developed during the 1970s, the performance they offered led to the suggestion that they would become the replacement for sand blankets. However, following extensive testing it was established that the pore opening size of these geotextiles was not sufficiently small to prevent the pumping of fines into the ballast. Further research in the 1980s showed that geotextiles could be used to reduce the sand blanket thickness, but not to totally remove it and the associated costs.
The stiffening effect created by geocells is designed to stabilise the ballast – which may help prevent pumping. However, without a physical barrier, fines are still likely to migrate into the ballast over time. As with sand blankets, the installation of geocells requires excavation so it’s a slow and labour-intensive process. Future ballast cleaning and tamping works may also be hindered as the geocell sits within the ballast build up.
Railway-News magazine Issue 4 Track & Infrastructure edition, November 2022: GEOfabrics - Trackbed Stabilisation Solutions from the Experts.
Railway-News magazine Issue 3, September 2022: GEOfabrics – Performance You Can Trust, Reinforcement Where It's Needed.
Railway-News magazine Issue 4, September 2021: Geofabrics - Clearing the Route: CuTex Geocomposite – Root Barrier Inhibition.
Railway-News Magazine issue 3 2021: GEOfabrics – TrackTex Geocomposite – The ‘Once Only’ Solution to Mud Pumping
In 2010 Geofabrics launched a new anti pumping geocomposite in the UK, which could be used to prevent the development of mud pumping.
This paper describes the development process undertaken to produce a lightweight, geosynthetic filter to replace a sand-blanket used within trackbed.
RK4 - a textile/grid composite, was installed to stabilise the ballast/subgrade interface and reduce the upward movement of subgrade fines.
TrackTex™ Anti-Pumping Geocomposite was used to to provide an increased form of ballast protection in known trouble areas in Christiansburg, Virginia.
TrackTex anti-pumping geocomposite was selected by Network Rail as a method of preventing mud pumping and prolonging trackbed performance.
Geofabrics' CuTex copper composite root barrier protects rail infrastructure from Japanese knotweed.
GEOFabrics will be in attendance at Railway Interchange 2023 at the Indiana Convention Centre in Indianapolis, IN, USA.
TrackTex has been installed in a road railroad crossing in Illinois with no reported issues throughout its utilisation.
A statement from Gordon Donald, on the success of the Geofabrics Ltd versus Fiberweb Geosynthetics Ltd patent infingement case.
A statement by Gordon Donald, Managing Director of Geofabrics, regarding the judgement on patent infringement by Fiberweb Geosynthetics Ltd.
TrackTex was installed on a frequently trafficked diamond crossing as a long-term effective remedy to frequent fouling caused by mud-pumping.
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