Traffic continued to roll smoothly over one of Sydney's busiest bridges recently as the roadway was lifted to accommodate an exit to the new Lane Cove Tunnel.
Engineers employed by Thiess John Holland employed compact and powerful high-pressure Enerpac hydraulics from Coates Hire Industrial Service to precisely lift the northern side of the Reserve Road loadbridge over the Gore Hill Freeway to make way for the new eastbound transit lane.
The (700 bar, 10,000psi) lifting technology involved - including a series of extremely low height CLP Series Pancake Lock Nut Cylinders - is applicable to a broad range of bridge, road and tunnel infrastructure involved in civil works, resource developments and major construction projects.
Project engineer Michael Damo said three existing bridge piers - installed well before the $1 billion-plus project was designed - had to be removed from the path of a dual carriageway exiting from the 3.4 km twin, two / three lane tunnel under Epping Road and Stringybark Creek.
The tunnel, linking the M2 Motorway and the Gore Hill Freeway, will cut an estimated 15 minutes off a trip to the city.
To ensure minimum traffic disruption while replacing the old piers (Gore Hill Freeway is used by thousands of cars and trucks daily) Thiess John Holland had to pour the six new pillars under tight overhead room beneath the existing bridge then jack up the bridge to remove its old pot bearings and replace then with new bearings on the new pillars.
The bridge, spanning about 20 metres, was raised just 6mm by a series of mechanically synchronised 250-tonne Pancake jacks positioned on top of the new piers adjacent to their elastomeric pot bearings.
Coates Hire Industrial Services' Colin Chapman says the main issue to be addressed was the confined space - the lift did not require the sophistication of the latest PLC-controlled Enerpac Synchronous Lifting equipment (also used on bridge lifts) because of the relatively straightforward nature of the job once the Pancake jacks had been installed and traffic flows controlled to facilitate the lift.
"The 260-tonne CLP 2502s we used have plenty of stroke for jobs such as this - they go up to 45mm fully extended - but they are only 159mm high with their plungers retracted. With lock nuts for mechanical load holding, they are very safe and very simple to use. The beauty of the equipment from the client's point of view was that they could hire the specialist low-profile equipment needed for this single application then return it after the job was completed."
Mr Damo said that once the Pancake jacks had been positioned on the new piers running down the centre of the bridge, it was relatively straightforward job to synchronise them through one manifold to ensure an even lift. The synchronised lift of the centre of the bridge was handled from just one pump feeding all six jacks, so they moved in unison.
Traffic continued to use the bridge while the work was progressing - "We had to implement a traffic management plan," said Mr Damo. "We had to reduce the allowable speed on the bridge while parts of the job proceeded, but it was not a major long-term disruption because the timing of the lift was set to co-incide with low traffic volumes. It was a very smooth job using techniques that have been widely proven."
The Lane Cove Tunnel, expected to be completed in 2007, is a key link in Sydney's orbital motorway network connecting the Gore Hill Freeway at Artarmon with the M2 at East Ryde. Motorists travelling between Falcon Street and the M2 will bypass 26 sets of traffic lights.
The high-pressure (700 bar, 10,000psi) equipment employed on the project is available throughout Australia and New Zealand from Coates Hire Industrial Service and from the national sales network of Enerpac, which is part of the global Actuant Corporation.