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.
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.
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.
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:
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.
Aurecon seized the opportunity to use virtual reality technology and augmented reality headsets to create an immersive and educational site induction experience.
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
2. Induction solution
3. Project delivery benefits
(Live stream drone footage)
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.
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.
Learn more about the remediation of Dean's Head.