Keller has completed ground improvement works on one of Brisbane’s largest infrastructure projects – a scheme that promises to create an impressive entry to the city, while significantly reducing traffic congestion, improving road-user safety and boosting business development.
Kingsford Smith Drive is a major road into Brisbane, linking the central business district with the port, airport and quickly developing northern suburbs. Now the road is undergoing a major upgrade as part of a flagship A$650 million government project.
The scheme will see the road widened from four to six lanes to ease congestion and cut travel times by 30 percent. It will also improve public transport, deliver pedestrian and cycling facilities and create new green spaces.
In early 2018 Keller was approached by the project’s principal contractor Lendlease to provide ground improvement works on a 1km stretch of the road.
Jet grouting expertise
“This is a construct-only contract that will eventually see us install around 700 jet grouting columns of 1,500mm and 1,200mm diameter up to around 15m deep,” explains Keller Project Manager Benn Zabawa. “The road runs right alongside the river, so we’re jet grouting through the soft, silty marine clays into firmer clays to stabilise the existing roadway and riverbank and support the expansion.”
For Keller, the first phase of the project ran from last May to November, with the team constructing 600 of the columns. The team returned in March 2019 for another six weeks to complete the rest of the works.
One of the most notable challenges for the Keller team is the site constraints. “On one side we have the very busy road and on the other the river, so at times we’ve been jetting right up against the concrete kerbs delineating the road from the works,” says Benn.
Overcoming site constraints
Working so close to live traffic and pedestrians, with only enough room for one rig instead of the client’s preferred two, has required rigorous planning from the Keller team. “Our works have been well planned, with a lot of coordination between the engineering and project managers, and the field supervision to ensure we stay on schedule, minimise impact of deliveries during rush hour and, of course, protect our workers and the public,” he adds.
“The ground is also littered with services, some known, some unknown, so we’ve had to be very careful. At one point we were jetting within a meter of a high-pressure gas pipe and the city’s main fiber optic cable.”
Ready for the final stage
One of the main features of the overall redevelopment is known as the River Walk, which opened in December and provides a dedicated pathway for cyclists and pedestrians adjacent to the road. It’s an attractive addition to the area but it meant the foundation piles for the cantilevered walkway were installed before the jet grouting, making installation trickier.
Despite the challenges, Keller has shown why it has an excellent reputation in this field.