Wellington Landmark made safe again
- May 7, 2018
- Posted by: admin-jonel
To the right of the Interislander wharf, a landmark familiar to Wellingtonians, is the old billboard frame. In days gone by, the frame controlled a viaduct bridge that connected a smaller freight dock.
When engineers discovered that the guy wires that supported the counterbalance weights had frayed and were at risk of breaking, the whole structure was scheduled to be dismantled due to its poor condition.
Ultimately the structure & surrounding wharf needed to be made safe
The requirement was to take the load off the wires in a safe, controlled manner, by lowering the counter balance weights to the wharf three metres below. A complicating factor was that the works had to be done within the existing steel structure, while assuming it had no remaining structural capacity.
The frame consists of two towers, with each tower housing a set of two weights to be lowered – overall an impressive total of 37.5 tons that needed controlled lowering.
Ultimately, after considering a number of options, it was decided to use four hollow core jacks, spacer stools and Freyssinet threaded bars to create a structure within each tower, which would enable workers to safely lower the weights onto the concrete flooring in a controlled manner.
Freyssinet, with the assistance of Jonel Hydraulics, devised a supporting framework and hydraulic lowering rig for each tower. The procedure was to connect four Freyssinet threaded bars to each weight, pass the bars through four cylinder/stool sets and then through a sequential hydraulic lowering and support blocking procedure.
The job was completed safely and on time due to meticulous preparation and careful execution of the works. – JOB DONE!