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Daniel Wallace, Seequent’s general manager of civil and environmental: “Leapfrog Works pairs a view of the geology with the engineering design to better communicate the associated risks in projects to stakeholders”

Aurecon and Seequent lead the way for digital engineering

Global engineering and infrastructure advisory company Aurecon, and Seequent, a developer of revolutionary visual data science software, are leading the way for digital engineering on New Zealand’s largest transport infrastructure project, Auckland’s City Rail Link.

Aurecon was awarded the role of principal technical advisor (PTA) to the CRL and is working alongside a consortium of engineers and architects to deliver the reference design. Ground risk is a critical factor on any major infrastructure project and has a direct impact on time and costs. Aurecon needed to do a detailed technical analysis of the ground conditions to identify the risks more clearly and then be able to communicate and mitigate these risks.

The use of Seequent’s 3D geological modelling solution, Leapfrog Works, enabled the team at Aurecon to achieve this.

Philip Kirk, geotechnical team leader at Aurecon, says: “This is linear infrastructure, so there’s no escaping challenging ground conditions when you’re building an underground railway and infrastructure. We didn’t want the construction team to encounter unexpected ground conditions that would compromise the project or delay it. We had to get it right.”

Complex geology

As well as construction of the tunnel, the CRL adds two new underground stations – at Mt Eden and Karangahape Road. When finished, it will allow trains to pass through most Auckland stations every 5 to 10 minutes at peak times. Put simply, the CRL will double the number of trains on the network, double the capacity of people on trains (to 30,000 an hour) and double the number of people living within 30 minutes of the city centre.

Auckland’s City Rail Link modelled in Leapfrog Works

The scale and location of this project poses challenges. The geology in the Mt Eden area of the project is particularly complex. There are three volcanoes, with quite different characteristics, to the north and south of the rail alignment. Over time, the volcanos have produced ash and lava deposits, which are mixed in with soft sediments from historical swamps and ponds, hard basalt rock, and sandstone.

Aurecon’s team undertook an extensive drilling programme to provide information on these underlying ground conditions. “Understanding the ground conditions and the insights gained through the drilling programme are crucial in terms of progressing and refining the design on the CRL,” says Mr Kirk. “We have already unearthed volcanic rock, soft sediment and reclamation material along different parts of the CRL route.”

Modelling the ground conditions

Over 200 boreholes have been drilled in various stages of the project, recovering almost 5 km of core. Historical records of over 1000 boreholes with over 
21 km of core from around the wider project area have also been used to understand and model the ground conditions.

Engineers and construction teams need to see how these ground conditions interact with structures so they can make informed decisions on structural design, the relocation of services, and construction methods. “Leapfrog Works has been an instrumental tool to support our ground engineering team, who are the interface between science and engineering,” says Mr Kirk. “Geologists need to be able to communicate the uncertainty in the ground conditions in a way that the engineers understand, relevant to the design.”

Built specifically for the civil engineering industry, Leapfrog Works provides a complete solution for fast and dynamic modelling of ground conditions, analysis of the interactions with the engineering design, and intuitive 3D visualisation. “A long-time challenge for the construction industry has been the disparate processes of designing infrastructure and ground engineering, from tender to feasibility to operational phases,” says Daniel Wallace, general manager of civil and environmental at Seequent. “Leapfrog Works pairs a view of the geology with the engineering design to better communicate the associated risks in projects to stakeholders.”

“A lot needs to happen in order to construct the tunnels in the area with the most complicated geology on the project. This includes relocating stormwater systems and bridges, and constructing several new structures within a tight corridor,” says Anita Nagy, engineering geologist with Aurecon. “Leapfrog Works was able to support the ground engineering team by facilitating better communication and interaction with our engineering design colleagues. The team were immediately surprised by how effective it was as a communications tool. This richer output of information is a vital tool for communication with project stakeholders. But even more importantly, it’s about getting the designs right from the start.”

Dynamic changes, positive outcomes

Leapfrog Works has helped Aurecon identify key opportunities in the reference design that will ultimately save time and money over the course of the CRL project. For example, shaft design details and ground improvement works at the Water Street shaft were revised and optimised to mitigate the ground risks in the area. This was an essential refinement to avoid project delays associated with inappropriate construction methods.

A great benefit of Leapfrog Works is the dynamic nature of the application. The Aurecon team were able change the ground model immediately, based on the live data coming from the onsite shaft borehole drilling. These changes to the model were then communicated quickly to the designer, who changed the types of pile to be used, thus saving the project team days and making sure the structure was as accurate as it could be.

Pat McLarin, product manager of Leapfrog Works, says: “We are really pleased that Leapfrog Works has been embraced by Aurecon on this major infrastructure project. The visualisation of the models is key and what that means in terms of risk and decisions to be made on the design. This has been really important to Aurecon’s ground engineers so that they can communicate more effectively to such a diverse group of stakeholders.”

“We hope this is just the start of using 3D visualisation to communicate risks within a project and to help clients and contractors make sense of them,” concludes Philip Kirk. “This is the power of combining technical eminence and digital technology.”

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