Spectra® Rail Railway Improvement System
The Spectra® Rail System allows the optimization of trackbed structure design with the use of Tensar® Geogrids. Stabilizing aggregate in rail ballast and sub-ballast layers, Tensar Geogrids stiffen the roadbed section, typically reducing the dynamic deflection that occurs at the surface for each load cycle by 40-50%*.
The Spectra Rail System:
- Decreases the required trackbed thickness without loss of performance
- Reduces track maintenance
- Reduces track settlement by preventing the vertical movement of sub-ballast particles into the underlying soft subgrade
- Maintains effective drainage of the trackbed by dramatically reducing the breakdown of ballast particles and preventing the upward migration of subgrade fines
- Diminishes wear and tear and extends service life of track mechanical components (rail, ties, fasteners, spikes, insulated joints, etc.)
- Mitigates ballast settlement and lateral creep
- Lowers up-front construction costs and speeds construction by reducing the amount of aggregate required
- Provides life cycle cost savings by extending ballast service life
- Improves performance and productivity by eliminating the need for speed restrictions on problematic sections of rail line
*See research results from the Transportation Technology Center’s test facilities in Pueblo, Colorado and overseas.
Savings at Installation
Tensar Geogrids can reduce the thickness of a sub-ballast layer up to 50%, saving up to $30,000 per linear mile of track (approximately 27% of total sub-ballast construction costs). In addition, the ease of installation not only accelerates construction schedules; it also eliminates the need for expensive, specialized labor and equipment. Geogrids installed directly over poor quality subsoil reduce or eliminate the costs associated with subgrade excavation, disposal and replacement, or with chemical treatment. With shallower excavation, the costs associated with the relocation of utilities can be reduced or eliminated as well.
Savings Over the Long Haul
Tensar Geogrids help preserve the integrity of the roadbed by confining the ballast layer. Under most site conditions, this extends the period between maintenance operations three to five times, significantly reducing long-term resurfacing needs.
Promoting Drainage by Inhibiting Fines
Effective drainage within a trackbed section is maintained by reducing the accumulation of fines. In a well-graded, mechanically stabilized sub-ballast, the aggregate provides a natural filtration barrier to prevent the upward migration of subgrade fines. In addition, the confinement of sub-ballast and ballast aggregate resists particle abrasion, further reducing the fines that are generated within the trackbed section. Tensar Geogrids provide the efficient, effective stabilization of sub-ballast aggregate that minimizes the intrusion and generation of fines, maintaining drainage of the trackbed and improving long-term performance.
Tensar Geogrids at Intermodal Facilities
Tensar Geogrids are also specified for the heavily loaded pavements required at intermodal facilities. There, loads imposed in the loading/unloading areas adjoining rail lines generally exceed those applied to normal roadbeds. These heavy-duty pavement structures must support loads not only from truck traffic, but from cranes and other cargo transfer equipment.
TriAx® Geogrid and the use thereof are protected by U.S. Patent No. 7,001,112.
