Keller has been appointment by the Victoria State government to undertake ground engineering work for three projects on its programme of level crossing replacement in Melbourne, Australia after recent successful complete of two similar schemes.
The programme will see more than 50 congested level crossings will be replaced with overbridges to improve safety and speed up travel times.
Keller has completed two schemes – one in Bayswater with Laing O’Rourke and Fulton Hogan and another in St Albans with CPB Contractors – and has now been appointed to complete a further three. The latest schemes involve installation of continuous flight auger piles at Skye Road in Frankston, bored retention and bearing piles for the Mernda Rail Extension and a bored secant retaining wall for the North East Programme Alliance.
Commenting on the work at Bayswater, Keller regional manager Diarmaid Long said: “The overall project involved removing the level crossings and creating a grade separation for a rail under road solution. So that the client could dig a corridor over a 1km decline, they required our expertise to construct the retaining walls, which were designed to protect the property and critical rail assets immediately adjacent to the excavation.
“Before the contract award, we worked closely with the client to develop a solution over several months to help them understand what would work and what wouldn’t. Once we’d won the contract, we then installed around 900 bored retention piles - 900mm and 1,050mm diamete - up to 24m deep over about eight months. This solution was the most efficient to meet the pretty tight programme constraints.”
At St Albans in western Melbourne, Keller was contracted to install retention piles for two rail underpasses and foundation piles for pedestrian bridges, a gantry and signal structures. The team installed around 500 bored piles at 600mm and 700mm diameter.
While the geological conditions in Bayswater with its stiff clays were relatively straightforward, the high-strength basalt at St Albans required an expert team and specialist Bauer BG30 and Mait HR drilling rigs. These provided the necessary power and manoeuvrability on what was a tight site.
“The main challenge for both projects was that we were working in built-up areas within live rail corridors and close to the public,” said Long. “This type of work always presents numerous safety, logistic and programming challenges. Many areas could only be accessed during weekend or short-term rail occupations, where 24/7 works and up to five rigs and 10 crews were required to ensure the client could fully utilise the trains being taken offline.”