Queensland Rail seek solution to conquer Hughenden monsoon seasons
Following an extended, La Niña affected, monsoonal wet season, Queensland Rail (QR) were experiencing more frequent track misalignments and increased maintenance costs with sections of track near Hughenden in North Queensland.
This region is synonymous for its “Black” soils, which once saturated become very unstable. Due to recent involvement with subgrade stabilisation on local Highway projects, Geofabrics were approached for suggestions with the potential to assist QR engineers.
QR decided on a series of three trials using the Geoweb® cellular confinement system to strengthen the track structure through the most severely affected sections. The three-dimensional Geoweb® honeycomb structure, works in load support applications, by generating powerful confinement forces through ballast / cell wall friction, creating a load dispersion structure with high flexible strength.
Each trial section comprised of short lengths of Megaflo® subsoil panel drain spaced at 20m centres, bidim® A24 nonwoven geotextile to maintain separation between the subgrade and ballast layers and then the 200mm deep Geoweb® panels were installed.
Each of the 2.5m x 8.4m panels were held expanded in place with evenly spaced steel stakes, which were later removed. The cells were overfilled by 150-200mm of standard rail ballast before levelling with large “Grader” type machinery.
A single layer of Tensar® SSLA30 geogrid was then installed, which will serve to maintain the ballast profile and further reduce maintenance costs.
The ease of installation allowed for the entire construction to be completed within short permissible track downtimes. QR, despite being extremely pleased with the progress to date, intend to monitor and asses the performance of the Geoweb® sections through the next wet season before recommending its use more widely across its rail network.