Hexham Straight Alliance

Project Summary:

The Hexham Straight Widening Alliance was established to facilitate the widening of a 6km section of Maitland Road from four lanes to six, spanning between Sandgate and Hexham. The project involved creating two additional lanes, one in each direction, alongside replacing the bridge over Ironbark Creek with two new structures and demolishing the existing one.

Maitland Road serves as a pivotal link in the National Land Transport Network, facilitating access to and from the Port of Newcastle. It bears some of the heaviest traffic volumes in the Hunter region, with approximately 50,000 motorists utilising this segment daily. The initiative seeked to alleviate congestion during peak hours and ensure Maitland Road is equipped to accommodate future growth.

Project Scope:

• Design responsibility for all packages (Design & Construct Alliance).
• Earthworks and pavements to facilitate widening of Maitland Road.
• Replacement of existing structure across Ironbark Creek with two new structures.
• Repair of existing and construction of new stormwater network.
• Upgrades to nine existing signalised intersections.
• Upgrades to local road and unsignalised intersections within the package sit.
• Utility relocations and protections including water, sewer, power, gas and communications.
• Adjustments to property accesses, bus stops and provision of new shared pathways.
• High Early Strength Slab replacements in Rigid Pavement.
• Slab Jacking of sunken pavements.
• Road furniture upgrades over the entire 6km length of the job to increase safety of motorists.
• Rectification of existing structures over high pressure gas trunk main.
• Working alongside sensitive environmental areas including RAMSAR wetlands, mangroves and national parks.

Key Challenges:

• Unsuitable geotechnical conditions, particularly soft soils, and high water tables which posed a risk to construction activities such as excavation, foundation laying, and pavement construction.
• High traffic volumes in the project area presented a major challenge, compounded by limited space for construction activities. The need to maintain traffic flow while carrying out essential works demanded meticulous planning of work zones, traffic diversions, and temporary closures to minimise disruptions.
• The proximity to the Hunter River introduced complexities related to environmental considerations, water management, and flood risk mitigation. Construction activities adhered to strict regulations to safeguard the river ecosystem, prevent contamination, and mitigate the risk of erosion or flooding.
• The area was densely populated with various underground utilities, including water mains, communication lines, gas pipes, and electrical cables. Managing the relocation or protection of these utilities posed significant challenges, exacerbated by the presence of unknown or poorly documented services. Comprehensive utility surveys, innovative detection methods, and ongoing coordination with utility providers were essential to avoid service disruptions, minimise project delays, and ensure the safety of workers and the public.

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