Demolition Methodology

The current development application outlines a methodology to dismantle the bridge in pieces using heavy machinery located on the river bank and floating work platforms.

The Contractor has proposed a change in demolition methodology due to current condition of the bridge and concerns over work on the bridge causing unmanaged collapses of bridge material.

To change demolition methodology, the Contractor must lodge an application for an Amended Development Application.

The application to change demolition methodology will be submitted in the coming week and its review will run concurrently with works onsite.

Initial work being undertaken over the coming months is common to both current and changed methodology, allowing the amendment to be assessed without further delaying the project.

Due to common works involved in site preparation, no unnecessary work is being undertaken, nor is contractor operating outside current conditions of consent

Proposed change of methodology

‘Induced collapse’ is a common technique for bridge demolition that removes the need for intensive work on unstable structures at height and reduces the possibility of truss failure during manual dismantling.

Induced collapse involves the systematic/sequential removal of key structural members through the application of force to result in the controlled collapse of the structure.

Because the application of force to remove key structural members is done remotely via the use of small charges, this method minimises the need for prolonged work activity by individuals on a deteriorating and dangerous structure.

Additionally, the structure is collapsed to ground level where it can be then dismantled on the ground rather than trying to dismantle them at height.

Any loose timbers or material will be cleaned from the riverbed using a longreach excavator with a sieve bucket.

This will be followed by rehabilitation of the site and then demobilisation of all plant and equipment.

Pylon Removal – Amended Application

Council resolved last year to proceed with the complete demolition of the bridge including the removal of the pylons. This decision was based on the inability to re-use the pylons for new River crossings and the cost of ongoing maintenance of pylons to ensure they were not an ongoing water hazard.

The current approved development application for the project has issued a condition to retain the pylons as part of heritage conservation.

An application for an Amended Development Application will be lodged by the Contractor, requesting the condition of consent requiring the retention of the three pylons be amended to allow for the pylons to be removed as per the resolution of Council.

This application will contain information to support Council’s original request to remove the pylons and will be submitted in the coming weeks.

The bridge demolition was undertaken in 2014.

Find out more about the Hampden Bridge Legacy Project.