Project description

The project involved widening an 800-metre section of the Central Coast Highway at Erina Heights from one to two travel lanes in each direction with additional lanes for cyclists, buses and parking. It included:

• signalisation of two major intersections
• earthworks, cut and fill of 25,000 cubic metres
• design and construction of a 1400 square metre reinforced soil retaining wall. This was 11 metres high in places and included Modified Type-F safety barrier
• stormwater drainage structures including reinforced-concrete pipe culverts and major scour protection structures
• construction of 18,000 square metres of heavily bound pavement to RTA specification RN73.

The challenges were:

• environmental management, including erosion and sediment control
• major relocations of public utilities
• traffic management
• major property adjustments including earthworks, drainage, construction of retaining walls, concrete driveways, fencing and gates, and landscaping.

Traffic management

Traffic management included design and construction of temporary arrangements while construction continued. Particularly, this allowed all traffic movements to continue while the finished surface level at Matcham Road intersection was lowered by two metres and the roundabout at Serpentine Road was removed to be replaced by traffic signals.

Major public utilities

Our involvement with utilities included installation, removal and relocation.

• Energy Australia: relocation of high and low voltage assets from overhead to underground, using a Level-1 prequalified subcontractor, and construction of new 132 kilovolt ducting and joint bays for future use. We liaised with Energy Australia regarding inspections, outage arrangements and cut-overs.
• Gosford City Council: installation of 824 metres of 150 mm water main using Council prequalified subcontractor including. We liaised with Council regarding inspections, cut-overs, temporary supply arrangements, and connection and relocation of house services.
• Telstra: installation and relocation of new man-holes, underbores, ducting and cabling and temporary relocations for construction.

Environmental management

The project operated under a licence from DECCW, with the following requirements:

• Construct and maintain sediment basins, undertake flocculation, water quality testing and dewater.
• Restrict working hours and notify residents of any out-of-hours work

We undertook stringent inspection and maintenance of erosion & sediment controls with daily inspections by our own staff and fortnightly inspections by the client's Environment Officers and soil conservationists.