Railway construction can involve many challenges -- from track support over weak subgrade conditions to bridge abutments and sediment control. As experts in mechanically stabilized earth (MSE) solutions, Tensar International developed the Spectra Rail Railway Improvement System to increase the service life of rail track substructures. Tensar Geogrids, in combination with aggregate, are used to stabilize sub-ballast and ballast layers, decreasing required roadbed thickness while improving track performance. A cost-effective alternative to conventional solutions, the Spectra Rail System has proved to save significantly on installation and life cycle costs as well.
Tensar TriAx Geogrids stabilize ballast and sub-ballast layers through the principle of “mechanical interlock.” When unbound aggregate is compacted over a geogrid, the coarser particles partially penetrate through the geogrid apertures and lock into position. As the aggregate layer stiffens, the load distribution over the underlying subgrade is enhanced, increasing its effective bearing capacity. Shear forces imposed within the aggregate layer as a result of trains passing are thereby partially transferred into the geogrid.
In addition, the geogrid’s ability to confine aggregate particles significantly reduces lateral spreading of granular particles, a major cause of ballast and sub-ballast settlement. TriAx Geogrids offer strength at low strain in all directions, preventing large deformations within the aggregate. The rigid triangular apertures of TriAx Geogrids are designed to interact with typical railroad ballast and sub-ballast materials to ensure optimum mechanical interlock. Geogrids with larger apertures (for example, Tensar TX190L) are used to stabilize the coarser aggregates typically used for ballast layers.
By significantly reducing the required trackbed thickness, Tensar TriAx Geogrids can typically save up to $30,000 per linear mile of track. The ease of geogrid installation not only accelerates construction schedules, it also eliminates the cost of special labor and equipment. With the option to install Tensar TriAx Geogrids in wet conditions, contractors can maximize their productivity in inclimate weather.
Since Tensar TriAx Geogrids can be installed directly over existing weak subgrade soils, the costs associated with subgrade excavation, disposal, and replacement or chemical treatment (along with the set time for chemical treatment) can be eliminated. With shallower excavation, the potential costs associated with the relocation of utilities can be eliminated as well.
Over the long term, Tensar TriAx Geogrids preserve the integrity of the railway structure by confining the ballast and sub-ballast layers. This typically extends the period between maintenance operations by a factor of three to five times and the design life of heavy-duty pavements at intermodal facilities by three to six times. In reducing the deflection of the trackbed during loading, Tensar TriAx Geogrids also extends the life of mechanical track components including rails, ties and insulated joints.
As the worldwide leader in geogrid technology, Tensar is committed to the success of your rail stabilization project. Our products and technologies are backed by the most thorough quality assurance practices in the industry. We provide comprehensive design and site assistance for every stage of a Spectra Rail System project, often leading to a more reliable and economical design.
Given a specific set of soil and proposed loading conditions, a full design section can be developed by Tensar to include a trackbed section in full compliance with AREMA guidelines as well as pavement sections for intermodal facilities.
Rely on the experience, resources and expertise that have set the industry standard for nearly three decades.
In addition to the Spectra Rail System, Tensar offers solutions for railway site development projects including: