Heathcote Road – Platipus® Anchors

Heathcote Road is a major arterial road connecting Sydney’s southern suburbs to the M5, M7 and Princes Highway. To alleviate congestion and improve road capacity, a 2.2km section will be upgraded to four lanes. The project includes five road bridges, crossing waterways, other roads and electrified rail. Where the road crosses Harris Creek, the southern embankment required cutting almost vertically below the existing road to allow room for machinery to install the bridge piles for the new structure. As the existing road was required to remain open during construction, the cut face required stabilisation to provide a safe work area and to support the live load from the road above.

A second batter also needed stabilising as part of the rail upgrade, with a 70° cut required to enable a 750T crane to setup and install the bridge beams over the rail corridor.

DESIGN

The stabilisation design was split into two stages either side of Harris Creek. The 37m long north side and 33m long south side 70° cut faces would be stabilised using Platipus B6 Civil Anchors, set into fill and medium dense sand. On the second batter section, near vertical faces were cut and stabilised using Platipus B8 anchors All anchors would be installed with 400mm x 12mm steel plates over the top of geotextile and wire mesh

INSTALLATION

The embankment was cut in 1m stages, with Platipus Anchors placed at each level to stabilise the slope. This created a 70° slope while keeping the road open to traffic and reducing the risk of collapse. Testing of the soft material ensured that load requirements were met. Once the anchors were cut, piling rigs and cranes could safely access the site for bridge construction.

By using Platipus Anchors and smaller excavators, Ertech sped up the process and reduced costs, allowing them to self- perform part of the work to stay on their scheduled programme.

The Platipus Anchors system provided the following benefits to the project:

• Can be installed using small excavators
• Can be installed in tight site spaces
• The slopes are instantly stabilised one loadings are met
• The Platipus anchor system can be installed and tested quickly with no specialist drilling equipment