3D GIS -

Modelling Basalt

for Auckland’s

City Rail Link

ProjectMatthew Faulk

Esri User Conference, Auckland

August 2013

2

Agenda

1. City Rail Link – an overview

2. Geology of central Auckland – Basalt

3. The Challenges - Engineering and GIS

4. The GIS solutions

5. Analysis Tools – 3D Analyst

6. Visualisation - ArcScene

7. Communication – ArcGIS Online / ArcGIS ArcExplorer Desktop

8. Conclusions and wrap up

3

City Rail Link – an overview (1)

4

City Rail Link – an overview (2)

Above images – courtesy Auckland Transport http://www.aucklandtransport.govt.nz/improving-transport/city-rail-link/Pages/crl-route.aspx

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Geology of central Auckland – Basalt (1)

http://www.teara.govt.nz/files/p-8706-gns.jpg

East Coast Bays

Sedimentary

Erosion Surface

Basalt Lava

Flows

Volcanic Ash

6

Geology of central Auckland – Basalt (2)

Mt Eden

(Maungawhau)

7

The Challenge (engineering perspective)

Retaining wall

along this sectionTunnel to surface

approximately here

Modelled Basalt

Current

topographic

surface

8

The Challenge (GIS perspective)

9

Generating a Basalt Volume

1. Extract borehole data from Geotechnical team gINT® (224)

2. Full Intersection (59)

3. Finished Within (45)

4. Digitise additional data

5. Basalt interpreted extent

6. Extent points

7. Full dataset (689)

8. Create Base RL of Basalt (raster and TIN model)

9. Create Top RL of Basalt (raster and TIN model)

10. Create a basalt model volume

The GIS solutions – Methodology (1)

Borehole Status

FULL INTERSECTION

FINISHED WITHIN

NOT KNOWN

NOT PRESENT

NOT RECORDED

Borehole Status

FULL INTERSECTION

FINISHED WITHIN

NOT KNOWN

NOT PRESENT

NOT RECORDED

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Creating a tunnel from the

alignment

• Polyline Z file from design team

• Buffer 3D based on the track

centreline (6.8m outside

diameter)

Calculating volumes around the

basalt / tunnel intersect

• ‘Intersect 3D line with

multipatch’

• Mapped extents of intersection

• ‘Intersect 3D’ to produce

volumes of basalt

The GIS solutions – Methodology (2)

3.4m

960 m³

1660 m³

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Many 3D Analyst toolbox items used

Tunnel

• Buffer 3D

Basalt

• Add surface information (top of basalt)

• Raster Interpolation (IDW) Base and Top RL surfaces

• Raster to TIN• Extrude Between

Buildings/Stations

• Layer 3D to Feature Class

Volumes

• Enclose Multipatch• Intersect 3D Line with Multipatch• Intersect 3D• Add Z information

Analysis Tools – 3D Analyst

3.4m

12

Visualisation - ArcScene

13

3D Model shared using ArcGIS

Online and ArcExplorer

• Author .mxd with data layers

• Save maps and layers as

map/layer packages

• Data uploaded to AGOL (using

the Organisational Account)

• Share and view the ArcExplorer

map via desktop application

Communication – ArcGIS Online / ArcExplorer

14

• Engineering Perspective:

• Provides a visual representation

for Engineers (v. Google Earth)

• AGOL facilitated a collaborative

portal for communication

• Geology perspective:

• Only useful for visualisation

• Not a true technical model

• Too much model maxima /

minima (‘peaky’)

Conclusions and wrap up (1)

15

GIS Lessons Learnt

• Edge effects around ‘Extrude

3D’ (Knowledge Centre)

• 3D analysis – computer

intensive so consideration for

model parameters

Next steps

• Model refinements (more data –

using ModelBuilder)

• Surface algorithms (smoothing)

• Identified further data

acquisition areas

• ArcExplorer Analysis Tools

Conclusions and wrap up (2)

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I would like to thank the following

• Philip Kirk (Aurecon)

• Anita Nagy (Aurecon)

• Steve Hawkins (Auckland

Transport)

• Dave Mockett (Aurecon)

• Cameron Irvine (Aurecon)

• Auckland City Council /

Auckland Transport

Acknowledgements

Thanks and Questions?