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Digital Expertise: Case study

Deans Head Christchurch – Digging the dirt digitally

A city to rebuild

In 2010 and 2011 Christchurch was shaken by a series of devastating earthquakes. In September 2010, the city was awoken by a 7.1 magnitude earthquake. This was followed on 22 February 2011 by a massive 6.3 magnitude aftershock which struck near the heart of the city. Already weakened buildings and infrastructure were severely damaged, completely destroyed or rendered useless due to the intense ground shaking and liquefaction of soils.

An insight into the damage

An insight into the damage at Deans Head Christchurch after the 2011 earthquake

An insight into the damage at Deans Head Christchurch after the 2011 earthquake

Delivering a vision for the future

As the city rebuilt, Aurecon was closely involved in the deconstruction and geotechnical work around the region. The collective stories relating to rebuilding the city were filled with sadness and loss but there were incredible tales of resilience, renewed strength and hope for a brighter future.

“The rebuild of Christchurch was about recreating and planning for a new, resilient community that will be as vibrant as it always was. Deans Head is just one of Aurecon’s many and varied projects that contributed to the rebuild of Christchurch,” says Dr Jan Kupec, Aurecon Technical Director.

Steadying the slope for life to carry on

In the aftermath of the Canterbury earthquakes, the steeply sloping residential area of Deans Head in Sumner posed a serious threat to the access of the Sumner township. It had the potential to disrupt the lives of more than 7 000 residents. Earthquake shaking had caused a repeated retreat of the cliff edge, with over 25 m of cliff edge toppling off the 80 m high and 350 m long cliff face. The adjacent residential area of Deans Head was left in a highly unstable state and identified to be at risk of further massive landslides.

In the event of additional cliff collapses, the community faced the possibility of being isolated from Christchurch, particularly as the main road into Sumner was situated directly below the cliff.

The government needed a feasible long-term solution which a traditional slope remediation solution could not provide. The answer was removing an estimated 53 000 m3 of landslide debris and effectively removing the hazard. Land Information New Zealand (LINZ) commissioned Aurecon as the key advisor for all Deans Head remediation engineering services including civil, geotechnical, structural and surveying.

300 shipping containers were the temporary solution to keep the road operational in Deans Head after the landslide

300 shipping containers were the temporary solution to keep the road operational in Deans Head after the landslide

Digital solutions improve safety and model topography

From the outset, Aurecon’s innovative, digital solutions changed the way this project was tackled.

Contractors needed to work in high risk areas that had previously been inundated by cliff collapse material. Therefore, it was essential to assess and monitor the impact of boulder roll in the work area. Using remote controlled machinery, contractors first excavated a catch ditch at the base of a cliff and constructed a bund. As a result, there was a need to accurately reflect this change in topography.

Bespoke digital innovation deployed at Deans Head included:

  • Using photogrammetry to capture the constantly changing environment
  • Developing detailed virtual reality models
  • Employing augmented reality to create solutions
  • Capturing live drone footage for use in public consultation and Q&A sessions

Flying an unmanned aerial vehicle (UAV), the team collected 1000s of photographs and through photogrammetry, created 3D models.

Modelling and managing the site

  1. Rockfall modelling was initially done using 2010/ 11 LiDAR data, which was accurate to 0.5/1m
  2. The Fly-Model-Analyse workflow was introduced by Aurecon
  3. Fly: Remote controlled drones scanned every part of the slope and captured 1000s of high resolution photographs
  4. Model: A 3D photogrammetry terrain model was created using the images from drones
  5. Analyse: Now the latest accurate topography model could be used to undertake 2D rock fall analysis so the excavation crew could operate efficiently and safely

Digital tools measure removal progress and costs

You could fill 20 Olympic-sized swimming pools with the spoil removed from the Deans Head project. Aurecon was faced with the challenge of working out how to ‘verify’ contractor payment claims based on calculating bulk earthwork volumes.

A unique workflow was developed and deployed: flying an unmanned aerial vehicle (UAV), the team collected 1000s of photographs and through photogrammetry, created 3D models. This innovation was the first of its kind to compare complex 3D terrain models for volume purposes.

  • 1000s photographs taken to form a 3D site model
  • 3D photogrammetry model created from drone flights
  • 20 Olympic-sized swimming pools worth of earth removed
  • Able to verify contractor payment claims from highly accurate 3D data

Rethinking safety and site inductions

Aurecon seized the opportunity to use virtual reality technology and augmented reality headsets to create an immersive and educational site induction experience.

Man using virtual reality goggles

The team took 360° photo sphere images of the site around and overlaid the geohazards and site information. As the geotechnical engineers on the project Aurecon, was responsible for inducting contractors and drawing their attention to any hazards. Keeping everyone on site safe was a top priority.

On traditional geotechnical projects site inductions would have involved 2D maps and paper forms. Using virtual reality goggles for site inductions meant that contractors didn’t step foot onto the project site until they were fully inducted. It also made for an engaging way to be inducted to site and a very unique way to encourage participants to remember, and recall, the information.

“This changed the way we engaged with those accessing site and were able to clearly point out the hazards and illustrate the no-go areas, all before we even go to site,” says Tom Revell, Aurecon Engineering Geologist.

1. Induction challenges

  • How much hazard information to include in the VR induction?
  • Too much information led to the image being crowded and details lost
  • Too little information, details inaccurately communicated

2. Induction solution

  • Editable images using virtual reality technology made it easier to add, update and remove information
  • With two virtual reality goggles it meant that more contractors could be inducted at once

3. Project delivery benefits

  • Using virtual reality meant the time taken for site inductions was reduced by 50 percent
  • This had a flow on effect of reduced labour time for our client
  • Safety information effortlessly communicated to site contractors
  • This meant site staff were inducted before they set foot on the project site

Climb every mountain quickly!

Video Transcript: Deans Head Remediation - Christchurch, New Zealand

Simon York, Advanced Design Technologist

So, one of the projects that I showed in AU this year was a site that came about because of the earthquakes that hit Christchurch about six years ago. It's a cliff site that used to have houses on it and, unfortunately, most of these houses were lost in the earthquake.

Our role in the project is to monitor that site as the site is remediated, so that means a lot of materials can be removed from that site to reshape the whole site. It soon became obvious that AUVs were going to be a pretty powerful tool in this project. Initially there was a use of abseilers to inspect the cliff, especially after any aftershocks that happened. We were able to quickly implement use of UAVs though to perform those visual inspections and the use of reality capture tools such as Recap and Remake from Autodesk, soon became really powerful to be able to use to capture photos from the UAVs and then run those through to create models of the site.

What are the benefits of this technology?

So much time saved in that process, also just the accuracy – the ability to have a real representation, a 3D model of that site, on a weekly basis so we can now go back over the last six months and actually see where things have changed the entire time. I've been trying to promote throughout the business, the use of reality capture tools on every project, not just open lands type projects. I see it as being hugely valuable for building services and building structures. The ability to capture the existing buildings and have that data available to you when you’re designing, but also in the construction process. So, why shouldn't we be scanning buildings weekly as they've been constructed so that we know what’s happened on the site week-to-week and see where the changes have happened.

(Live stream drone footage)

How we met a digital time challenge

At one stage of the project, Land Information New Zealand (LINZ) challenged Aurecon to bring what our engineers were seeing via their drone to a desk in the LINZ office, and to do it in real time. The client challenge was to make this happen within 24 hours. We accepted it with relish.

After testing hosting software, and only 22 hours after receiving the request, Aurecon was hosting its first ever YouTube live feed of a site from a drone.

  • Within 24 hours, remote viewers across the globe had access to footage of the geotechnically high-risk site in real-time
  • The experience was interactive and participants could even give prompts as to where the UAVs flew around the site
  • During the live flight a Q&A session was running to enable discussion of what the viewers were seeing
  • Viewers from New Zealand, Australia, America, Ireland, South Africa and the United Kingdom tuned in to see the footage
  • Value was created by making the digital insights more accessible to a wider audience in real time

Immersing our stakeholders

Using an online viewer and simple VR headsets, the client could see the models in a relatively immersive environment.

The 3D models that were created from drone footage and 2D drawings were dropped into virtual and augmented reality using HoloLens. The process of drone to photogrammetry to interrogation of models using HoloLens was an industry first.

Using an online viewer and simple VR headsets, the client could see the models in a relatively immersive environment. The introduction of Microsoft’s HoloLens enabled Aurecon to take this experience to the next level by viewing the models on multiple headsets in augmented reality.

The models could then be interrogated by several engineers at once allowing them to pick up features that hadn’t been noticed previously. Health and safety hazards could be discussed prior to visiting the site and it was also used to predict workflow clashes or logistical issues prior to works starting.

Using an online viewer and simple VR headsets, the client could see the models of T2T in a relatively immersive environment.

Learn more about the remediation of Dean's Head.


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