Case Studies

Polyfabrics Stabilises Aurizon Rail for Years to Come

September 24, 2019

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Location: Gracemere QLD
Products: EGRID3030 & TerraTex 464 Geotextile


Project Overview

The customer, Australia’s largest rail freight operator and rail transporter of coal from mine to port for export markets. With operations in all states of Australia,  hauling more than 500,000 tonnes of coal per day. The Wiggins Island Rail Project (WIRP) creates a vital link between the new Wiggins Island Coal Terminal in Gladstone, and the mines in the Southern Bowen and Surat basins. Leighton Contractors were awarded the Rocklands to Stanwell track duplication which is a key component of the WIRP

Key Challenges 

This project involved 18 kilometres of track duplication serving coal trains up to 1.7Km in length. With each wagon potentially weighing in excess of 100T, the tracks needed to withstand huge cyclic loads. These loads, coupled with an extensive design life resulted in the use of biaxial geogrids for strength and stabilisation in the track design.

The Solution

Polyfabrics’ EGRID 30KN biaxial geogrid was approved as the geogrid of choice. The EGRID 30KN tensile strength and the 3.9m roll width suited the design requirements.

The new track bed was excavated to a typical depth of 750mm, adjacent to the existing rail line. The EGRID was used in 2 layers. The first EGRID layer  was  placed  in  fill with CBR20. The following layer of EGRID was placed in fill CBR45 to bring the level of fill  to  formation  level.  The thicker sections and nodes of the  EGRID minimise the  risk of installation damage when compared to other geogrids on the market.

A heavy geotextile was also required on some sections of the rail duplication where low subgrade CBR’s were found (CBR<3). Polyfabrics supplied TerraTex 464 Geotextile for this application in roll widths of both 4m and 6m.

The Customer had a very tight timeframe on the project and product availability was a key element. In total Polyfabrics supplied:

  • Over 200,000m2 of EGRID 3030
  • Over 30,000m2 of TerraTex 464 Geotextile
  • Various subsoil drainage products

The Results

The benefits of EGRID on this job:

  • The geogrids structural junctions, rigid ribs and thick walls helped lock aggregate, increasing its shear resistance and providing lateral restraint under vertical loads.
  • Distribution of loads and therefore reduction in stress concentration over the soil
  • Increase in load distribution (Bearing Capacity Increase)

The qualities outlined above translated to reduced fill thickness which results in:

  • lower excavation and fill costs
  • faster construction time
  • improved design life 
  • a major reduction in the carbon footprint of the project  


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