Remote-operated digger enters cathedral in world first

The cathedral was severely damaged in the 2011 Christchurch earthquake. Photo: Star News
The cathedral was severely damaged in the 2011 Christchurch earthquake. Photo: Star News
A remote-operated digger has started to clear out debris, masonry and some significant biohazards, as well as retrieve heritage items from Christ Church Cathedral which was badly damaged in the 2011 earthquake.

The project - a world first - marks the start of the major interior clean-up in Christchurch and is another milestone in the cathedral’s reinstatement journey.

Controlled from an operations centre outside the church using specially fitted cameras with live stream capability, the remote-operated digger is an innovative digital solution to keep workers safe.

It has also permitted the cathedral’s interior clean-up to begin early, allowing the project’s critical work plan to gain about three months.

Project director Keith Paterson said: “Introducing a remote-operated digger is a safety-first approach that solves health and safety issues by keeping personnel out of the building while still getting the work done.

"A manned digger would be at risk of falling debris or building collapse were an earthquake to occur at this stage of the project.”

Personnel from Protranz Earthmoving Ltd and Aurecon, which first suggested the use of the remote-operated digger, are operating it.

“We don’t have line of sight of the digger inside the cathedral, we can only see it via screens inside the operations centre,” said Simon Gaynor, Protranz commercial manager. 

“In preparation, we set up a testing area that mirrors the internal geometry of the Cathedral and have been rehearsing over the past few months to get comfortable with the kit and ensure we could proceed safely.”

Aurecon design technologist Simon Yorke said: “The remote camera system includes five individual cameras fitted at different points on the digger to relay real-time video back to the operations centre outside.

"A sixth camera, located inside the Cathedral, gives the operator a bird’s eye view of the location of the digger.”

With the safe retrieval of heritage fabric, a top priority for the Christ Church Cathedral Reinstatement Project, the digger is carefully focusing on specific areas.

“We know there are several items of interest inside the nave, such as the old font," said Paterson.

"The digger will move carefully through the areas we think these items might be located in the hope we can retrieve them. Our heritage professional will then sift through everything collected to find any precious items before the rest is disposed of."

A special enclosure has been built on the cathedral worksite to provide a wash down area for the digger and to allow skips to be removed and re-introduced. The remote-operated digger will be working in the building for the next six weeks.

In March this year, the roof of the cathedral was removed as part of the deconstruction phase of the rebuild.

Stabilisation work - the critical pathway efforts before actual rebuilding begins - on the 140-year-old Gothic-style church building began in May 2020.

After years of public rows and wrangling, the Anglican Synod voted in 2017 by a narrow majority to reinstate the building.

Christchurch City Council granted a critical resource consent which allowed for the repair and restoration of heritage fabric along with the replacement of the west porch, tower and vestries on the main building.

- additional reporting NZ Herald 

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