Rail Track Rehabilitation Over Problematic Subgrade
Despite weak subgrade, rail track rehabilitation with Neoloy®Geocells improved durability, sustaining track geometry
As part of its program to upgrade and rehabilitate track and construct new lines, Israel Railways adopted the Neoloy Geocell technology as its preferred method for track rehabilitation over problematic subgrade. This includes improving load support over soft sandy soils and restraining volumetric change in fat clay soils.
A new 16 km Southern rail line from Tel Aviv passes through a number of suburbs, originally built over sand dunes. Whereas, the route passes through weak subgrade, the rail authority and geotechnical consultants decided to utilize Neoloy Geocells to reinforce the substructure along the entire line. In addition to improving the load bearing capacity, Neoloy was selected for its overall performance, durability and long-term cost savings in track operations and maintenance.
Conventional subgrade improvement methods include thick layers of expensive ballast and subballast and/or the use of geogrids for reinforcement. However geogrids require high quality subballast aggregate, while their zone of confinement is limited. Reduction of the subballast layer is minimal, and these solutions require frequent maintenance.
Neoloy Geocell Solution
The Tel-Aviv to Ashdod rail line utilized Neoloy Geocells of 20 cm wall height for subgrade reinforcement of the subballast layer. A total of 200,000 m2 is being installed in 12m wide sections along the 16 km rail route. Medium grade, fine granular infill material was sufficient for the heavy load support needed for the railway substructures. Whereas, the Neoloy vertical zone of influence provides 30-50% more confinement and reinforcement than other solutions, attrition of the aggregate and ballast infill is reduced significantly. The result is that track geometry is sustained for longer periods of time thereby reducing the number of expensive maintenance cycles.
- Reduction of required excavation depth
- Reduction in periodic maintenance and rehabilitation
- Cost-effective rapid installation
- Facilitates faster speeds and heavier loads without track degradation
- Field testing showed that track maintenance cycles with Neoloy Geocells can be extended by 3x