//1 May 2023 1

Stephen BrooksSenior EngineerSafety, Technical & Engineering: Buildings & Civils

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

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

/

16,000 Route Km190,000 earthworks55,000 examinations

1 May 2023 2

Network Rail earthworks in numbers

/1 May 2023 3

National aerial survey overview

Ortho FCIROrtho RGB Oblique

LiDAR DTM DSM

/1 May 2023 4

Earthwork examinations

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

Each examiner will measure slopes ever so slightly differently

/1 May 2023 5

Earthwork examinations

Some earthworks are more extreme than others

/1 May 2023 6

Earthwork failures

/1 May 2023 7

Earthwork remediation

/1 May 2023 8

Earthwork failures: Harbury Landslip

/1 May 2023 9

Harbury – One year later

/1 May 2023 10

Exam question

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

/1 May 2023 11

Principles of methodology – adding heights to the points

/1 May 2023 12

Principles of methodology – connecting the spot heights

/1 May 2023 13

Principles of methodology – identify break points

/1 May 2023 14

Principles of methodology – extract the slope info

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

/1 May 2023 15

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

We are now in the process of analysing all five chain length to verify examined geometries.

/1 May 2023 16

Multiple cross sections - classified

/1 May 2023 17

Multiple cross sections – filter results

/1 May 2023 18

Manual versus automatic geometry extraction

/1 May 2023 19

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’

/1 May 2023 20

Manual versus automatic geometry extraction

/1 May 2023 21

Multiple cross sections – relating back to 5 chain lengths

/1 May 2023 22

DTM vs automatic slope extraction

/1 May 2023 23

Buffering the slope objects

/1 May 2023 24

Never Inspected - 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.

But what else could we do with the data?

/1 May 2023 25

Conclusions

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

Always develop a methodology that:• is produced in conjunction with subject matter experts• produces output using language that SMEs understand• has flexible parameters and is scalable.• has systematic and logical data management• is well documented.

//1 May 2023 26

Stephen BrooksSenior EngineerSafety, Technical & Engineering: Buildings & Civils

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

Thank you