The Auckland Harbour Bridge (AHB) Cable Supports and Strengthening Project was part of Transpower’s North Auckland and Auckland Grid Upgrade Project. The project involved the installation a new underground high voltage cable link between Pakuranga and Albany.
The AHB is a critical link between Auckland Central and the Northshore for a wide variety of critical infrastructure services and in order to support the new high voltage cable, significant modifications and upgrades had to be made to the existing bridge structure.
This specifically included the removal of 3km of existing timber kerbing and installation of 1,600m2 of fibreglass reinforced plastic grating and 70 tonnes of new steel. The work involved drilling, blasting, painting, bolting and welding of the existing bridge structure.
There were a number of health and safety and logistical challenges to contend with over the course of the works. This included significant amounts of work at height (up to 45m above water over a busy shipping lane), sharing the site with bridge maintenance contractors and tourism operators as well as a high level of manual handling in difficult to access areas. In particular the works involved the installation of a series of 600 OD steel pipes, over 20m long and weighing approximately 2 tonne. These pipes were installed and connected to concrete piers in the North Concrete Viaduct using cranes and elevated work platforms positioned on a barge. Due to the limited headroom available underneath the bridge deck, a purpose built lifting attachment was used to position the pipes in place.