Emerald Hill Track Slew

Summary

The project includes the constructionof a 4,455 metre Track Slew between 488.600-493.055km, includes the construction of 4 new culverts and the relocation of 3 existing signals.

It also includes 2 x provisional items which subject to available budget:

• Recon 1: 486.620 - 487.100 (480m)
• Recon 2: 487.500 - 488.00 (500m)

The majority of the embankment work has been constructed at an offset from the existing rail line.

This provides a 4.1m Excavation Buffer Zone between the toe of excavation and the nearest rail which allowed a significant amount of the works to be completed outside major closedowns.

The slew sections (tie-ins) at both the City and Country end of the new embankment required excavation work within the defined 4.1m Excavation Buffer Zone. As such these components of the work needed to be completed during major closedowns.

The five existing culverts also needed to be replicated and replaced. Three new culverts can be built in-line with the existing culverts, located at 489.565km, 490.125km and 490.500km. The two existing culverts, located at 491.83km and 492.440km, were replaced with a new single off-line culvert constructed at 492.120km to replace them.

Scope of Works

Delivery Of City Slew 488.600 to 489.160km (560m)

• All works associated with the formation and embankment construction beneath the City Slew area. Works include the removal and reinstatement of track onto the existing track alignment to achieve the required formation; and
• Removal and reinstalment of affected signaling equipment, booking out and booking back in affected signaling infrastructure including testing and certifying signaling integrity.

Delivery Of Country Slew 492.724 to 493.055km (331m)

• All costs associated with the formation and embankment construction beneath the Country Slew area. Costs include the removal and reinstatement of track onto the existing track alignment to achieve the required formation; and
• Removal and reinstalment of affected signalling equipment, booking out and booking back in affected signalling infrastructure including testing and certifying signalling integrity.

Rail Embankment Works Outside the 4.5m Buffer Zone

• Grubbing of embankment footprint;
• Excavation & placement of Site Won Fill to achieve subgrade levels;
• Placement and mixing of Gunnedah Stockpile materials with Site Won Fill to achieve subgrade levels;
• Trimming, compaction and preparation of subgrade, including placement of geotextile and geogrid for new rail embankment;
• Placement and compaction of all Structural Material for new rail embankment;
• Placement and compaction of all Capping Material for new rail embankment;
• Placement and compaction of all Bottom Ballast for new rail embankment;
• Receipt and construction of 1,980 metres of new ARTC supplied perway on design alignment to lesson track build scope in possession;
• All works associated with the relocation of the track onto the new formation and design alignment;
• Construction of 4 new culverts;
• Removal of all the redundant culverts and associate works;
• Reshaping of redundant (old) railway embankment and placement of generated spoil as per the Works Description. Includes spreading, compaction and installation of erosion and sediment controls;
• Construction of down side access road from recycled materials; and
• Installation of fencing and gate to restrict access into the corridor at the Up side entrance to site off Goolhi road.

Achievements

• Successful management of excessively wet subgrade between the two existing culverts, located at 491.83km and 492.440km. This resulted in the removal of wet material, drying out and replacement all conducted during winter months while experiencing regular rain events;
• Achieving a quality with working to very stringent safety requirements;
• Management of the local quarry to achieve necessary delivery rates and to produce a compliant material based on a tight specification. To achieve this Daracon called upon its internal quarry division to supply a Pugmill and conduct material product testing to achieve a blend that would meet the client’s requirements as the natural product through traditional quarry processes was unable to achieve this;
• Project only having a single access so the scheduling of works was critical;
• Working remotely with workers living away from home; and
• A significant amount of working including the installation of 3 of the 4 culvert was completed safely adjacent to live rail.