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Stephen BrooksSenior EngineerSafety, Technical & Engineering: Buildings & Civils

https://uk.linkedin.com/in/stephenrbrooks

Evaluating & managing earthwork assets with GIS*(*without getting my shoes muddy)

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16,000 Route Km190,000 earthworks55,000 examinations

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Network Rail earthworks in numbers

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National aerial survey overview

Ortho FCIR

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Earthwork examinationsEarthwork examinations

Earthwork inspections cost Earthwork inspections cost between £50 - £120 per five between £50 - £120 per five chain lengthchain length

There are 190,000 earthwork There are 190,000 earthwork assets across the UKassets across the UK

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Earthwork examinationsEarthwork examinations

Some earthworks are more extreme Some earthworks are more extreme than othersthan others

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Earthwork failuresEarthwork failures

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Earthwork remediationEarthwork remediation

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Earthwork failures: Harbury LandslipEarthwork failures: Harbury Landslip

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Harbury – One year laterHarbury – One year later

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Exam question

Are we confident that we know where all our earthworks are and the associated geometry information is correct?

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Principles of methodology – individual cross section

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Principles of methodology – identify the centre point

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Principles of methodology – adding heights to the points

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Principles of methodology – connecting the spot heights

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Principles of methodology – identify break points

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Principles of methodology – extract the slope info

Now repeat this process every 20m along the rail network(That’ll be 800,000 cross sections)

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Applying the methodology – Never Inspected

In September 2015 we had 36,000 sites that were never inspected.

By April 2016 we had less than 6,000

80% of the 30,000 records were removed without the need to set foot on track.

This involved analysing 150,000 cross sections and over 15m spot heights

Manual inspections of these sites would have cost in the region of £1.2m

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Multiple cross sections

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Multiple cross sections - classified

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Multiple cross sections - slopes

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Multiple cross sections – filter results

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Manual versus automatic geometry extraction

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Revising the methodology

Cutting

(Slope height and angle is calculated along entire length)

Cutting >3m Cutting >3m Cutting >3m

Embankment <3m

‘flat’

Cutting <3m

‘flat’ ‘flat’ ‘flat’ ‘flat’

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Multiple cross sections – filter results

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Multiple cross sections – revised methodology

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Manual versus automatic geometry extraction

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Multiple cross sections – relating back to 5 chain lengths

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DTM vs automatic slope extraction

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Buffering the slope objects

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Buffering the slope objects

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Final Outputs

The never inspected analysis examined 150,000 cross sections and 15m spot heights.

We are currently rolling the methodology out nationally to verify presence of all earthworks regardless of inspection status. This involves: •Interrogating 47,000 raster tiles•More than 800,000 cross sections•Over 81 million spot heights

Once finished we will have a complete picture of all NRs earthworks assets, including detailed geometry, measured from a consistent perspective for the first time ever.

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5m Contouring – proof of concept

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1m Contours – (generated, smoothed, filtered, classified)

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50cm Contours

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25cm Contours

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50cm Contours

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Conclusions

No one GIS system meets all requirements of such complex analysis•Collaborative use ArcGIS, ArcPro, ArcPy & FME

Always develop a robust but flexible methodology

Complex analysis requires comprehensive data management

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Stephen BrooksSenior EngineerSafety, Technical & Engineering: Buildings & Civils

https://uk.linkedin.com/in/stephenrbrooks

Thank you