TERRAM HYDROTEX® at Ardglen NSW

Overview

Completed in 1877 the Ardglen Tunnel is the oldest single line tunnel still in use.  Located at the summit of a ridge with steep grades in each direction the heritage listed brick lined tunnel is not only historically significant but also presents challenges in terms of operational efficiency and ongoing track maintenance.

Key Challenges

The sections approaching the tunnel are narrow and the steep gradings requiring the use of banker locomotives leading higher volumes than experienced elsewhere within the network. These areas are specifically prone to drainage issues and mudholes can develop if not rectified. Subsurface evaluation techniques such as GPR (Ground Penetrating Radar) are used to identify and correct any areas of potential failure.

Traditionally a Sub-ballast or capping layer would be installed to help prevent the upward thrust of the slurred clay, however this is difficult to install, maintain and expensive.

Solutions

TERRAM Hydrotex® has been developed to replace the needs of sub-ballast and capping layers. It was deployed near the entrance to the tunnel to deal with excess water around the track formation, by allowing water to pass through and push out sideways while keeps the clay back.

Strong, flexible and quick and easy to install TERRAM Hydrotex® is a nonwoven geocomposite consisting of a central filter media thermally bonded to two opposing robust needle punched geotextile filter layers. By preventing the upward passage of smaller particles (0.002mm) the permeable filter media provides a critical function as the membrane effectively desiccates any residual slurry.

TERRAM Hydrotex® is:

• Environmentally-friendly, By removing the need for a sand blanket or filter medium, excavation depth is minimised. As a result, there is a reduction in the amount of soil being taken away for landfill, and a reduction in the vehicles required to deliver materials. 1 truck of Terram Hydrotex is the same as 24 trucks of sub-ballast.

• Fast & Simple to Install. This process allows the trackbed to be installed up to 4 times quicker than the standard practice of using sand or sub-ballest.

• Cost-Effective, TERRAM Hydrotex®works efficiently to reduce costs for the client