Presto Geosystems
This article first appeared in the Railway-News Magazine Issue 1, 2022.
Every year, railroads dedicate a great deal of capital and resources towards creating and maintaining high-quality track profiles. Providing a well-designed track profile is the foundation on which a successful rail line operates.
With ballooning rail traffic carrying heavier loads than ever, and increased occurrence of extreme weather events, a stable track profile is essential for successful operation.
GEOWEB® geocells have been used in the track bed for rail applications worldwide for more than 40 years. Through an interconnected honeycomb-like network, the HDPE-based GEOWEB® Soil Stabilisation System provides apparent cohesion and strength to materials that would otherwise be unstable over soft subgrades. Geocells stabilise the ballast, reduce vertical and lateral stresses and limit ballast movement. Stabilisation within the geocell system provides a longer lasting track profile that extends rail service life, while also reducing maintenance cycles and recurring maintenance costs. Research has shown that geocells reduce settlement of the ballast foundation and can reduce required cross-section thicknesses by up to 50%. This is particularly advantageous where track beds must be constructed over soft soils. The reduction in thickness leads to cost savings, along with an accompanying reduction in carbon emissions due to decreases in aggregate processing, transportation, handling and installation. In general, geosynthetics offer tremendous potential in reducing carbon emissions from civil construction projects, in many cases by 50% or more.
North West Electrification Programme Case Study
In the United Kingdom, Network Rail encountered extremely soft soils with low shear strengths during track modifications to the North West Electrification Programme. Due to soft subgrade conditions, conventional track design methods resulted in cross-sections as thick as 1 metre. Poor soil conditions along the track route required a soil stabilisation solution to improve undertrack stiffness and provide a more cost-effective solution.
