Oak Flats

Reinforced Earth® Walls

South Coast, NSW, Australia
Roads and Traffic Authority
Roads and Traffic Authority
Fulton Hogan

The Princes Highway between Oak Flats and Dunmore was originally constructed in the 1930s and is no longer suitable for the traffic flows that it was required to carry.

Early planning by the Roads and Traffic Authority (RTA) identified a new road corridor, generally following the railway line. This new corridor was reserved in Shellharbour City Council’s town plan in 1986.

On 28 February 2007 a contract was awarded to Fulton Hogan to construct the new section of the Princes Highway between Oak Flats and Dunmore.

The new highway comprised a four-lane divided carriageway, with a grade-separated interchange linked to Shellharbour Road. Shellharbour Road was also upgraded to four lanes, matching the remainder of its link to Wollongong.

The new highway links the Oak Flats Interchange to the North Kiama Bypass and completes the program to provide a high standard four-lane highway from Sydney to south of Kiama.

The old highway will become a local road serving rural properties.

A key element of the project is the elimination of a railway level crossing at Dunmore. The solution:

a new interchange incorporating a new bridge over the South Coast Railway.

The new alignment eliminates a narrow winding section of the Princes Highway that previously had a poor crash history and contributed to congestion and delays during peak traffic flows.

The RTA provided a detailed specification pertaining to the architectural finish on the facing panels for the Reinforced Earth® walls required for various structures within the interchange.

A Vine Pattern finish as seen on another project (Carramar) was proposed for the majority of the wall. The challenge lay in developing three different types of additional feature panels, which incorporated shell designs. The shell designs were chosen to reflect that this interchange is the southern gateway to the Shellharbour Local Government Area.


The new interchange incorporates four bridge abutments, two for the bridge over the railway and another two for the road overpass that forms the interchange. The design of the rail overpass incorporates provision for a future railway station and local access road. The Reinforced Earth Company (RECO) was appointed to design and supply a total of 3141m² of Reinforced Earth® walls for this project.

RECO worked closely with project architects and sculptors running through several design iterations during the progressive development of the exact panel finish required by the RTA and Fulton Hogan. The end result was three distinct shell patterns.

The shell panels are scattered throughout the walls and will be visible from both the new Highway, by passengers on the south coast railway and by residents of the nearby Flinders estate.


  • There are numerous benefits of the new highway: Significant reduction in traffic congestion; improved traffic flow; improved safety with the elimination of a narrow winding alignment which was completely devoid of overtaking opportunities; the removal of right turns at the Shellharbour Road and Princes Highway junction; a flood free route and elimination of delays caused by trains on the level crossing.
  • Besides structural, construction efficiency and budgeting benefits, Reinforced Earth structures also offer limitless aesthetic and architectural possibilities. When Reinforced Earth is specified or selected in the earliest phases of a project, specialists from RECO can help owners, their engineers and architects to maximize the design possibilities, allowing architectural treatments to be easily accommodated. At RECO we continue to innovate in collaboration with our clients in order to offer the widest possibilities of architectural expression together with the assurance of Reinforced Earth Quality.

Project Specifications

Bridge Abutments
620m (total)
Design Load
Design Life
100 years
Vine Pattern Feature Panels

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