Transport Infrastructure

WBHO Infrastructure delivers innovative bridge solutions

Oct 07 2019

WBHO Infrastructure delivers innovative bridge solutions

WBHO Infrastructure is celebrating a major milestone on the Ellerton Drive Extension in New South Wales, successfully launching a 44 metre centre bridge span over the Queanbeyan River.

The milestone brings the construction of a 185-metre six span bridge over the Queanbeyan River and Barracks Flat Drive one step closer to completion.

Originally planned as a Super-T bridge, WBHO Infrastructure (WBHO-I) proposed an innovative design change to a post-tensioned concrete box girder bridge, minimising the impact of bridge construction on the local community and the environment and significantly minimising safety risks during construction.

“The bridge was redesigned as an incrementally launched box girder,” Project Director Yianni Stavreas explained. “That allowed us to increase the centre span from 38 metres to 44 metres, eliminating the need to construct substructure foundations in a sensitive waterway and protecting the riverbed and local fauna, including native platypus. Incrementally launching the bridge also eliminated a range of critical safety risks such as working over water, working at heights, heavy lifting and working over public roads.”

David McPadden, Executive General Manager Eastern Region, said new bridge construction was a key part of WBHO-I’s plan to expand its business and diversify its core capabilities in Australia. The company has set its sights on a series of new bridge construction projects across the country, confirming its commitment to the growth of the company in Australia.

“WBHO-I is a Tier 2 contractor with a reputation for quality of service and innovative solutions,” he said. “Our people specialise in complex bridge construction and our recent performance on road and bridge construction projects in New South Wales and Victoria confirms our ability to deliver complex bridge projects in live road and rail, while minimising disruption to local communities and protecting sensitive waterways.”

In a further example of the company’s innovative approach to bridge construction, WBHO-I recently completed construction of the Tourle Street & Cormorant Road Duplication Project in Newcastle, delivering a second bridge crossing over the Hunter River ahead of schedule. The new 11 span bridge measures around 340 metres long and has improved traffic flow for the 33,000 vehicles that cross the Hunter River per day.

The tidal environment of the Hunter River presented a significant construction challenge and instead of opting for a traditional coffer dam solution, WBHO-I’s project team developed an innovative pile cap solution. Precast pile caps ‘shells’ were built on land and then craned and fixed to piles in the river. The pier shells acted as a retaining structure, allowing the balance of the pile caps to be constructed in isolation to tidal influences and mitigating a number of environmental and program risks.

Meanwhile in Victoria, WBHO-I is part of the Netflow consortium, contracted to deliver the $1.8 billion Western Roads Upgrade public-private partnership. The scope of work includes priority road upgrades and more than 260 kilometres of road rehabilitation and maintenance across Melbourne’s west, including new bridge construction at Palmers Road, Derrimut Road, Doherty’s Road and the Princes Freeway-Duncan’s Road interchange, new bridge and existing bridge modification works at the Princes Freeway-Forsyth Road interchange and eight other bridge rehabilitation projects across the network. All of these projects involve safe working near or over live road or rail, requiring extensive interface with road authorities and rail operators.

At the Princes Freeway-Forsyth Road interchange, WBHO-I is widening an existing bridge over the Princes Freeway, and duplicating a bridge over a major metropolitan railway line with a new single span fully integrated Super-T bridge. Access is a major challenge, with construction of the two bridge structures taking place simultaneously and in very close proximity to one another. Two freeway exit ramps with significant grade differentials, a busy metropolitan train service, a live major freeway with daily traffic volumes exceeding 100,000 vehicles and interface with a high pressure white oil pipeline constrain the site even further, dramatically increasing construction complexity.

The bridge-over-freeway is built on existing reinforced earth walls, supported by existing piles. WBHO-I’s project team developed a methodology to extend the reinforced walls and pile through the existing straps by building new pile casings, allowing new piles to be installed through a new reinforced earth wall section without risking damage or deformation to the existing retaining wall. The project team worked closely with designers to confirm the condition of the straps and existing fill material on the retaining wall and to confirm that the residual design life was adequate.

The team has also modified its pier protection barrier design to minimise potential impacts on freeway operations. By raising the pile cap and combining it into the pier protection barrier, the team has eliminated the need to excavate and bench out close to the freeway and is able to use the pier protection barrier to support beam falsework, providing more working space and clearance to traffic. Similarly the new bridge-over-rail, complete with deflection and collision walls, is being constructed a mere six metres from the existing bridge structure.