The road ahead is looking safer and more efficient for vehicles crossing the Clarence River at Harwood, NSW, with the completion of a new bridge. The 1.5km bridge, which is the highest and longest crossing in the Woolgoolga to Ballina upgrade project, will eliminate the stopping of main traffic flow that the existing 1966 liftspan bridge required for vessels to make their way up and down the river.

The Pacific Highway Upgrade Project is Australia’s largest regional road infrastructure project and the Woolgoolga to Ballina upgrade is the final link in the Pacific Highway between Hexham and the Queensland border to be upgraded to four lanes.

Col Solomon, Transport for NSW Senior Project Manager for the bridge, has been working on the Pacific Highway upgrade since 1997 and said that what was once the site of heavy traffic build up is now a safe and efficient section of road. In time, this upgrade will contribute to regional growth, economic development and efficiencies in freight movements due to shorter travel times.

“The safety benefits and engineering achievements realised on a project of this magnitude will serve the people of NSW and Australia well for many decades to come,” Mr Solomon said.

The road to progress

The Woolgoolga to Ballina project is being delivered by Transport for NSW through their delivery partner Pacific Complete, which is a joint venture between Laing O’Rourke and WSP.

Transport for NSW, Pacific Complete, and its contractor partners worked together under the Woolgoolga to Ballina upgrade project framework to deliver the new bridge, which was procured using a standard design and construct contract.

Mr Solomon said the main contractor was Pacifico, a joint venture between Acciona and Ferrovial, and the designer was ARUP, based out of its Sydney office.

“The collaboration and methodology applied on the project allowed for a wider breadth of skills and resources contributing to the successful delivery of the project,” Mr Solomon said.

According to Simon Cross, Pacific Complete’s Section Manager for the bridge, the second crossing of the Clarence River at Harwood is one of the most significant elements of the Woolgoolga to Ballina Upgrade Project.

“We needed to construct a bridge with two lanes in each direction 30m above the Clarence River,” Mr Cross said.

“This allows current and future motorway traffic between Sydney and Brisbane to cross the river without interruption from maritime traffic, unlike the existing bridge which opens to allow tall vessels to pass through.”

While the old liftspan bridge over Clarence River served its purpose for an impressive 53 years, highway traffic came to an abrupt halt when the bridge lifted for vessels on the river. This led to traffic delays of up to ten minutes with vehicles queuing for between 500m to 1km. The new bridge’s impressive height and grading means that this problem can be completely eliminated for those using the new bridge.

The new bridge is situated 25m east of the existing bridge and runs parallel to it. The location provides many benefits, with the existing motorway and local road infrastructure alignments able to be reused, therefore minimising the amount of new site clearance and infrastructure required.

“The piers of the new bridge mirror those of the existing bridge, minimising the impact on marine traffic and reducing the degree of riverbed scour. It also enabled full compliance with the urban design and landscape plan for the project,” Mr Cross explained.’

Bumps in the road

While both Mr Solomon and Mr Cross agree that an emphasis on face-to-face communication between all stakeholders made for an effective working relationship, projects of this size often face major challenges, with the bridge being no exception.

“Raising 44 girders weighing 176 tonnes each from flat top barges to their final resting place 30m above the Clarence River required the use of a 750 tonne crawler crane operating in super-lift configuration,” Mr Cross said.

“This involved detailed planning by our own experienced team members and those from specialist marine contractor, Brady Marine and Civil.”

Another essential part of the project was setting up the onsite reinforced concrete precasting and post-tensioning facility.

“This massive factory production line manufactured the 144 main U girders, each weighing 176 tonnes, before a second production stream made the bridge parapet units,” Mr Cross said.

“The combined teams drove a continual improvement agenda for the facility and this ensured the high quality of these precast concrete components.”

Many environmental concerns were also factored into the project’s design and construction.

“The new bridge is located in an area of soft soils, with a high acid sulphate content,” Mr Cross said.

“The design of the piles was chosen to reduce the amount of soil displaced and exposed, utilising reinforced concrete infilled steel tubular piles.

“This allowed the contractor to pitch and drive the piles both onshore and in the Clarence River with the minimum of disturbance to the ground.

“The design of the expansion joints was reviewed in great detail and ultimately led to the selection and procurement of a modular expansion joint fitted with sinus plates to reduce traffic noise.

“This is the first time this system has been used in Australia and we believe it has led to a better outcome for the people of Harwood.”

The impact of innovative infrastructure

With the complexity of the bridge project and the many elements involved in its construction, the team needed to employ innovative processes to make the project as time and cost-efficient as possible.

Geophysical survey techniques employed during the first stages of investigation work provided early data about the rock strata below the bridge and added to the foundation design.

“This was subsequently verified using data gathered by using traditional geotechnical investigation rigs mounted on jack up barges,” Mr Cross said.

“We were able to reduce the number of traditional bore holes, resulting in cost and time savings.” A technique used to control ‘hogging’, or upward curvature of the main 44-metre-long girders, was also used. This involved a two stage post tensioning process in which the girders were lifted out of the moulds in the precast factory the day following casting as part of the first stage.

“The second stage of post tensioning was then delayed until the marine section was ready for the girders in the river,” Mr Cross said.

These innovative construction techniques have led to a bridge that was completed and fully functional by late 2019, making a significant impact on the local population and achieving a huge milestone in the Woolgoolga to Ballina Upgrade Project.

While the new bridge will improve efficiencies, the original structure has heritage associated with it and will remain as an essential connection between Maclean, Yamba and Harwood. It also retains the only footpath and cycleway across the river.

With the old and new working together, the crossing of the Clarence River at Harwood has never been easier. This, paired with the design ingenuity and complex construction of the huge bridge project, makes this section of the upgrade a particularly significant one, and one that Mr Cross is clearly passionate about.

“I believe that the new bridge is by far the most iconic structure of the Woolgoolga to Ballina upgrade,” Mr Cross said.

Key project facts

  • The bridge is the highest and longest crossing in the Woolgoolga to Ballina Pacific Highway upgrade, which includes 170 bridges
  • The bridge spans 1.5km with 620m of this distance being over water
  • It has 117 marine and land piles
  • It has 144 concrete girders which were built at an onsite precast yard, each weighing up to 168 tonnes
  • It has 35 piers, including 13 in the Clarence River
  • The bridge deck features a gradual rise to allow for the shipping lane maximum height of 30m above water level
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