Road Realignment Works in Dapto Almost Complete

Wollongong city council appointed Abergeldie Complex Infrastructure Pty Ltd as head contractor for the $5.7 million project in April 2013. The company has 20 years’ experience civil infrastructure construction, targeting more technically complex and challenging projects.

The Scope of Works

• demolition of existing single lane road bridge;
• earthworks for permanent adjustment to course of creek;
• creek bank and  bed geotextile and rock lining for stabilisation;
• relocation of  water main, overhead electricity cabling and street lighting;
• new stormwater drainage structures;
• concrete kerbing and guttering;
• construction and flexible asphalt paving over 0.5 km new two lane road;
• concrete approach road slabs to new bridge;
• road guideposts, safety barriers, lane markings and signage; and
• construction of  three span, 46.8m long, two lane road bridge comprising massed concrete  abutments, driven piles with concrete headstocks, and 57 precast prestressed concrete planks overtopped with 40MPa concrete slab.

Abergeldie used its own steel fabrication workshop in Regents Park, Sydney to produce railings and barriers for the project, but a conscious effort has been made to source nearly all other materials and services in the Illawarra area. Products such as asphalt, concrete, reinforcements, guardrails and fencing have all come from local suppliers. Services from local suppliers include water cart hire, crane hire, line marking, survey, traffic management, demolition and, landscaping, rock lining, and kerb construction.

Works have been carried out under live traffic conditions, with at least one lane of traffic kept open at all times. An additional safety concern has been that a private railway line crosses the eastern end of the new road alignment. Another complication is that demolition of the existing single lane road bridge required relocation of a Sydney Water Corporation potable water main and an Endeavour Energy cable which were supported by the pre-existing bridge structure. The communication and liaison plan for the project has included protocols for close consultation with Sydney Water and Endeavour Energy for construction of the new pipe and power lines and cutting in to the existing networks.

The project also  has required realignment and stabilisation of the creek bed. “A temporary cofferdam was used for flow diversion to redirect the course of the creek under the new bridge,” said Michael Boyle, Abergeldie’s Managing Director. “It was a very tricky process, mostly because of heavy rainfall we experienced. We had to install extensive environmental controls to prevent flooding of the construction area and at the same time redirect the creek flow to align with the position of the new road bridge crossing. The high level of water flow meant that the creek wanted to keep to its natural existing path and there was a risk of erosion of the banks of the new alignment until we had the new earthworks fully stabilised. We put a lot of detailed planning and supervision into the environmental management and erosion control works and were able to achieve the cut over from the old creek alignment to the new without any environmental incidents occurring.” said Boyle.

With the bridge construction now complete, asphalt has been laid with the wearing course  to be placed after the completion of all permanent tie-in works. The traffic switch to the Western side of the new alignment has now taken place and landscaping is currently underway.

Works continue on the Eastern side of the alignment. Works to be completed include the construction of the South bound lane pavement at the Southern and Northern tie in to Shone Ave, relocation of the Sydney Water potable main and milling of the existing road. The pre-existing bridge has already  been partially demolished with the remaining part of the bridge to be demolished following the relocation of the water main. Re-alignment of the creek East of Shone Ave is now complete.  With current progress, the project is forecasted for completion end of February 2014.

Abergeldie constructs civil, marine, tunnel, water and wastewater and mine infrastructure across Australia and New Zealand. The company’s mission is to build the complex infrastructure needed to build better communities.