Lifting, holding and lowering bridge construction

Situation

The ‘Ara Tuhono: Puhoi to Warkworth’ project,  a 4-lane extension (18.5 km) to the Northern Motorway (SH1) from the Johnstone's Hill Tunnels, at Puhoi, to tie-in with existing SH1, north of Warkworth, to improve the safety and connection between Northland and other parts of the North Island (Auckland, Waikato and Tauranga). Part of this project is the Moir Hill Road Bridge (weight: 1400 ton), one of the in total 7 bridges during the project.

Challenge

Meccanico, New Zealand’s specialist in heavy lifting and levelling operations, needed to lift and hold the Moir Hill Road bridge 4 mm, so the bearings could be repaired. The lifting took places in increments of 1 mm and every step the weight was monitored via a screen. This handling was required at both ends of the bridge. After completion of  the bearing adjustments to the abutment of the bridge, the bridge had to be lowered back onto the bearing. 

Solution

To ensure safe and controlled lifting, lowering and levelling of bridges and other heavy properties, Meccanico used a flexible, easy to handle and extremely accurate synchronized lifting system. Because complex lifting procedures also often require ‘tilting’, this feature was a 'must-have' in the system.

In 2017 Holmatro had developed a 2,000 ton synchronized positioning system for Meccanico with the option to determine the center of gravity (COG) and be able to weigh the load if necessary. The system is equipped with 6 double-acting pump units, each with 4 individual oil flows for all the 24 lifting points. Due to the modular set up of the system, the pump units can be placed around the object and then connected together. Thanks to this set up, the distance from the pumps to the lifting points can be kept equal and limited to the bare minimum. This results in much more stable lifting and lowering with significantly less vibration. The modular set up also provides huge flexibility; the system is easy to control and move around, without the need for any additional equipment such as a crane or fork lift: A major benefit on job sites where access is difficult and cranes cannot get access.

The pumps are linked together by means of a data cable that is connected to a portable HMI (Human Machine Interface) complete with touchscreen. The software on the system allows the user to set the exact parameters  required to execute a complex lift. Should something fall outside of the given parameters (for instance an unexpected shift in weight) the system automatically stops the lift, so that the user can safely check and secure the object before recommencing the lift.

Due to the double-acting cylinders, the user has maximum control both on the lifting and the lowering action as gravity is not relied upon to lower the load. 

Holmatro’s synchronized positioning system can easily be up-scaled by adding more pumps and cylinders, giving it an almost unlimited capacity in terms of lifting, lowering, levelling and weighing.

This makes the synchronized positioning system flexible and multi-usable in various applications and projects, like another Meccanico application; the lifting, lowering and levelling of earthquake-damaged properties. 

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