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DESTinationRAIL, 26-27 April 2018, University of Zagreb

Simon Abbott – Professional Head of Geotechnics simon.abbott@networkrail.co.uk

Experiences of Earthwork Management

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Risk definition

2

Risk = Likelihood x Consequence

Con

seq

uen

ce

of ris

k e

ven

t

5

4

3

2

1

A B C D E

Likelihood of risk event

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TOP GEOTECHNICAL CHALLENGE Detection of asset failure by

means other than train drivers

£3m remote failure detection pilot looking at

rapid failure of soil cuttings

Risk Bow Tie, Tech Roadmap & Challenge Statement

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WCM1 in Scotland: November 2015

Example: Significant Event (failure) 50+

F

F

A

I

L

E

D

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Western: Kemble (Jan 17)

Wessex: Milborne (Mar 16) Scotland: Murthat (Nov 15)

LNW: Watford (Sept 16)

Further examples of notable events

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Organisation Roles and Responsibilities (Simplified !)

6

Safety, Technical & Engineering Route Businesses

Technical authority and assurance body. Set the overall

direction and corporate strategies for safety, environment,

asset management and engineering. Owner of asset policies,

risk control frameworks and the innovation / R&D pipelines.

Owner of route assets with day to day accountability for the

safe management of the infrastructure. Plan and deliver

inspections, maintenance and renewals of assets in line with

corporate policies to achieve agreed objectives.

Prof Head of Structures

Prof Head of Tunnels & Mining

Prof Head of Drainage

Prof Head of Buildings

Capability Groups

- Principal Engineers

- Senior Engineers

- Engineers

Prof Head of Geotechnics

Director(s) of Route Safety

and Asset Management

Route Asset Manager(s)

(Discipline Specific)

- Senior Asset Engineers

- Asset Engineers

- Assistant Asset Engineers

Route Managing Director(s) Chief Engineer

Chief Civil Engineer

MD of Route Businesses Group Director of STE Director of Digital Rail Managing Director of IP CEO

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Capital investment improves safety, reliability and weather resilience BUT legacy issues relating to knowledge at the time of construction

will continue to be a root cause in many earthwork failures

RELATIVE

PRIORITISATION

– targeted investment to manage

network risk. Pro-active and

sustainable asset management

RELIABILITY – justified intervention and

investment from targeted monitoring to

prevent failing assets impacting operations

FORECASTING

DETERIORATION

Relative prioritisation requires informed decision making

with competent staff, effective tools and processes

RECOVERY – reactive restoration FAILURE IMPACTS ON UK PLC

FUTURE

PROOF

FAILING ASSETS

RESISTENCE (& resilience)

TO WEATHER - quantifying

challenge to industry.

Multi-control period

journey to achieve

Big Data

Collection &

Management

Strategic &

Tactical Models

Analytics &

Algorithms

Data Cleaning

& Validation

Continuous

Improvement

OUR KEY DRIVER

IN RESPONSE

Global Stability Resilience

Appraisal (GSRA) completed

2017 – quantifies threat from

legacy construction issues

Core activities

today using

Earthworks

Safety Risk

Matrix in pro-

active asset

management

Strategic long term journey

to address gap in weather

resilience – rate of change

relative to appetite and

availability of funding

CHALLENGES IN

MANAGING EARTHWORKS

Preventative (predict)

Preventative

(pre-determined)

Maintaining Reliability

Improving Reliability

Broader NR

terminology in

maintenance

effectiveness

Corrective

Earthworks: Challenges and Key Drivers in Response

DE

CR

EA

SIN

G

DA

TA

VO

LU

ME

& I

NC

RE

AS

ING

D

AT

A V

AL

UE

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• Control Period spend for CP5 forecast outturn of £680m. Strategic Business Plan (SBP) recently published

shows a total of £793 for CP6 (17% increase)

• Three asset types each with unique challenges:

• embankments provide biggest performance challenge (accounting for up to 8% of TSRs per period)

• soil and rock cuttings provide greatest safety risk and continue to cause significant events

Long term improvements becoming apparent, with

safety events reducing particularly from cuttings.

However, inherent legacy construction issues will

always provide challenges for weather resilience

(or resistance)

A high level overview of management and safety performance

Continuous improvement over

the last 20 years in a range of

areas including:

• Staff numbers & competence

• Policy

• Asset management

• Inventory database

• Weather management

• Strategic planning

• Work bank management

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Individual topics I could talk about in great detail today….

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Natural slopes in lower consequence locations (Loch Eilt)

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February 2013

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Winter 13/14 – DfT review commissioned

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Bradwell Abbey - LNW (October 2013)

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Improving problematic cuttings

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Preparatory Condition of Asset Base

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PROBABILITY

UN

CE

RT

AIN

TY

Increasing chance of occurrence

0 1.0

From: Lee, E.M 2009. Landslide Risk Assessment. QJEG, Vol 42, p445-458.

A Brief Timeline

1. 1995 – Fatality at Ais Gil landslip

2. British Rail – Soil Mechanics

Division sold off. Maintenance

gangs with local knowledge

dispersed following privatisation

3. Early 2000’s – recruitment of first

specialist Area / Territory

geotechnical engineers

4. 2001/02 – Earthwork TSR reporting

commenced

5. 2003/04 – Earthwork volume

reporting commenced

6. 2004/05 – Earthwork Failure

reporting commenced

7. 2005/06 – Electronic data capture

of defects commenced during

earthwork inspections

8. 2012 – Asset specific Earthwork

Policy Issued for the first time

9. 2014/15 – Evidence based

statistical examination system

deployed into business

10. 2016 – Asset inventory complete

Inc

rea

sin

g e

xp

loita

tion

of k

no

wle

dg

e a

nd

eva

lua

tion

of ris

k

Probability / Uncertainty / Confidence

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Geotechnical Asset Definitions

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NR/L3/CIV/065: Examination of Earthworks

Capturing Earthwork Asset Information

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Typical Defects and Movement Indicators

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SSHI

29 7-Jul-15

• Put in place in NW Zone in 1997 (Post Ais Gill)

• 2001 review recommended national use (as

basis for first 065 standard)

• Systematic examination of observed parameters

• Based around 5 failure modes (Rotational,

Translational, Earthflow, washout and burrowing)

• Potential and Actual failure indicators

• Parameter weighting by expert judgement:

• 16 possible SSHI scores

• Serviceable, Marginal and Poor categorisation

(banding of 16 scores). Emotive terminology.

• REM (subjective assessment) used to adjust

SSHI weightings

• Refs: Manley and Harding, 2003, Babtie, 2004

Soil Slope Hazard Index (SSHI)

/ 7-Jul-15 30

Clarborough: 27th April Loch Treig: 26th June Rosyth: 18th July

Bargoed: 30th January St Bees: 30th August Barrow: 27th December

Enforcement action in 2012/13

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Wettest Winter on Record – 2013/2014

7-Jul-15 31

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Improvements in assessing safety risk

to this from this

FURTHER INFO SEE:

Power, C., Mian, J., Spink, T., Abbott, S., Edwards, M.

(2016). Development of an Evidence-based

Geotechnical Asset management Policy for Network

Rail, Great Britain. The 3rd International Conference on

Transportation Geotechnics. Procedia Engineering.

Volume 143, p.726-733.

Catalyst for improvement came from events of 2012/13

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Risk definition

33

Risk = Likelihood x Consequence

Con

seq

uen

ce

of ris

k e

ven

t

5

4

3

2

1

A B C D E

Likelihood of risk event

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Geotechnical assessment

Severity of impact

Consequence – safety impact

34

Earthwork

failure

Debris on

track or track

undermined

Track not

affected

Train

derails

No

derailment

Collision with

another train

Train falls down

embankment

Collision with

obstacle

Rapid

deceleration

Emergency stop

Controlled

incident

Incre

asin

g s

eve

rity

Fatalities &

Weighted

Injuries (FWI)

1.0 Fatality

10 Major injuries

200 Minor

injuries/major shock

1,000 Non

reportable minor

injuries/minor shock

Asset Criticality

Score

Earthwork Asset

Criticality Band

(EACB)

/ 7-Jul-15 35

0

10

20

30

40

WholePopulation

Failures

% O

cc

urr

en

ce

0

5

10

15

20

WholePopulation

Failures

% O

cc

urr

en

ce

e.g. Slope angle < 15 deg and height < 3m

e.g. Slope angle > 35 deg and height > 10m

Negatively

weighted

parameter

Positively

weighted

parameter

All ~200

parameter

values

Total

Hazard

Index

Split into 5

Earthwork

Hazard

Categories

SCHI and SEHI Analysis Process

Earthworks Hazard Category

• Statistical likelihood of failure

• 2 orders of magnitude range for SEHI and SCHI

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Predicting failure

36

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

A B C D E

Per

cen

tage

dis

trib

uti

on

of

asse

ts/f

ailu

res

EHC Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution

Asset distribution

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Predicting failure

37

Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution

0

20

40

60

80

100

120

140

160

180

200

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

A B C D E

No

rmal

ised

pro

bab

ility

of f

ailu

re

Per

cen

tage

dis

trib

uti

on

of

asse

ts/f

ailu

res

EHC Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution

Asset distribution Normalised probability of failure

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0

20

40

60

80

100

120

140

160

180

200

0%

5%

10%

15%

20%

25%

30%

35%

40%

45%

50%

A B C D E

No

rmal

ised

pro

bab

ility

of f

ailu

re

Per

cen

tage

dis

trib

uti

on

of

asse

ts/f

ailu

res

EHC Asset distribution Asset distribution Normalised probability of failure - SSHI Normalised probability of failure - EHC Failed asset distribution

Predicting failure

38

Asset distribution Normalised probability of failure Failed asset distribution

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Preliminary Assessment

of Slope Stability

(capability)

4-May-18 39

The legacy threat

A pragmatic approach today

Acquisition of better data Assessment of slope stability

Continuous Improvement – quantifying the legacy threat

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National Aerial Survey

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National Aerial Survey

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0

2

4

6

8

10

12

14

16

18

20

00.511.522.533.544.555.566.577.58

Slo

pe

hei

ght

(m)

Slope angle (Cot B)

Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage

Cross Asset Risk

All Assets Upper bound Lower bound

Global Stability Resilience Appraisal (GSRA)

42

1

cotB

B

Low

vulnerability

Moderate

vulnerability

High

vulnerability

High plasticity clays – Deep seated failure – High pore water pressure

11° 14° 18° 27° 45°

Stability chart

boundaries vary with: • Geology

• Failure mode

• Pore pressure conditions

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0

2

4

6

8

10

12

14

16

18

20

00.511.522.533.544.555.566.577.58

Slo

pe

hei

ght

(m)

Slope angle (Cot B)

Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage

Cross Asset Risk

All Assets Failed Assets Upper bound Lower bound

43

1

cotB

B

Low

vulnerability

Moderate

vulnerability

High

vulnerability

High plasticity clays – Deep seated failure – High pore water pressure

11° 14° 18° 27° 45°

Stability chart

boundaries vary with: • Geology

• Failure mode

• Pore pressure conditions

Failures mainly in high

vulnerability

Global Stability Resilience Appraisal (GSRA)

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0

2

4

6

8

10

12

14

16

18

20

00.511.522.533.544.555.566.577.58

Slo

pe

hei

ght

(m)

Slope angle (Cot B)

Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage

Cross Asset Risk

EHC A assets EHC B assets EHC C assets EHC D assets

EHC E assets Upper bound Lower bound

44

1

cotB

B

Low

vulnerability

Moderate

vulnerability

High

vulnerability

High plasticity clays – Deep seated failure – High pore water pressure

11° 14° 18° 27° 45°

Stability chart

boundaries vary with: • Geology

• Failure mode

• Pore pressure conditions

Failures mainly in high

vulnerability

FoS & condition poorly

aligned • Failure vs precursors

• Progressive failure

• Extreme weather events

• Degradation rates vs

inspection interval

Global Stability Resilience Appraisal (GSRA)

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0

2

4

6

8

10

12

14

16

18

20

00.511.522.533.544.555.566.577.58

Slo

pe

hei

ght

(m)

Slope angle (Cot B)

Deep-seated stability chart - Cuttings - D4 - High to Highest Drainage

Cross Asset Risk

EHC A assets EHC B assets EHC C assets EHC D assets

EHC E assets Upper bound Lower bound

45

1

cotB

B

Stability chart

boundaries vary with: • Geology

• Failure mode

• Pore pressure conditions

Failures mainly in high

vulnerability

FoS & condition poorly

aligned • Failure vs precursors

• Progressive failure

• Extreme weather events

• Degradation rates vs

inspection interval

Challenges: • Combined approach to

improve predictability

• Historic interventions

• Vegetation impact

Low

vulnerability

Moderate

vulnerability

High

vulnerability

High plasticity clays – Deep seated failure – High pore water pressure

11° 14° 18° 27° 45°

Global Stability Resilience Appraisal (GSRA)

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Presentation Title: View > Header & Footer 46

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Better exploitation of track data to identify problems

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• Earthwork examination algorithm; an evidenced based statistical

approach to quantifying the annual failure probability

• Parametric study undertaken to calibrate parameters against the

earthwork failure records

Actionable limits for track

Improvements could be made to existing processes if statistical evidence demonstrates the predictive

capabilities in the identification of previously failed embankment assets over and above non-failed assets

The challenge is to demonstrate that false positives are not continuously flagged out for evaluation.

Parametric study to consider:

• Failed embankment data set

• Sub-surface monitoring sites that

show failure is taking place

• Earthwork hazard categories

• Capital investment plans

Not always treating the root cause

Recipe Algorithm

Rich source of data

Continuous improvement in understanding deterioration

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11th August 2016

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Winter Failures

0

20

40

60

80

100

120

140

160

0.00% 50.00% 100.00% 150.00% 200.00%

Win

ter

Eart

hw

ork

Failu

res

Winter Rainfall (% LTA)

Winters (Dec-Feb)

13/14

15/16

/

Approach to Weather Trigger Levels

4-May-18 54

% SEVERITY VALUES

Rain

fall

Se

ve

rity

(%

)

SMI Severity (%)

Define zones around the failures cluster to correspond to Normal, Alert,

Adverse, Extreme weather.

Normal

Alert

Alert

Adverse

Extreme

Correlating Weather to Earthwork Failures

► Ongoing work….challenging and no utopian position

► Historical SMD trends poor…..new approaches use SMI and Rainfall

/

Selecting boundaries

► Picking thresholds has to achieve a balance

► Requires routes to but into operational impact

4-May-18 55

TRADE OFF

More weather

warnings

Few failures in

‘Normal’ weather

More ‘Normal’

weather

Many failures in

‘Normal’ weather

Low

thresholds

High

thresholds

► Trialled 40 different combinations to achieve the best overall balance.

► Starting point / aims:

∙ 85% Normal Weather frequency

∙ 3-7% Adverse Weather frequency

∙ 1-2% Extreme Weather frequency

Correlating Weather to Earthwork Failures

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Pursuit of opportunity to detect failures before trains

TOP GEOTECHNICAL CHALLENGE Detection of asset failure by

means other than train drivers

Tilt-meters Pilot

Study & further roll

out to soil cuttings

TECH 9

TRL: 7 IRL:tbc

££

£3m Pilot study is still within the roll-out phase of deploying

instrumentation to 180 assets (0.09% of the asset base).

/ Presentation Title: View > Header & Footer 57

Summary and conclusions

• Reducing number of potentially high consequence earthwork failures is the result of continuous

improvement, the introduction of an asset specific policy and an increase in staffing numbers of

engineers managing the portfolio.

• Climate change and increased demand for greater usage on the network will provide longer term

risks for which we shall continue to work with academia and research groups to further our knowledge

and understanding. Asset degradation is starting to be understood with greater confidence.

• It is recognised that continued capital investment is required to progressively strengthen our

infrastructure slopes. The rate of this investment will depend on the needs of other asset groups and the

difficult decisions that are continually made for the benefit of the whole railway system. Various criteria

need to be considered for the optimum trade-off between cost, risk and performance.

• Stopping trains from finding failed earthworks that have rapidly lost the ability to perform is our

top geotechnical challenge. We recognise that we have to improve our mitigations to reduce the

consequence of asset failure once it has occurred. The rapid failure of soil cutting slopes across of

infrastructure is difficult to predict and the acceleration of deformation is often the result of local rainfall

events that can be difficult for meteorologists to accurately predict with suitable confidence.

• We do not know what the technology of tomorrow will be but we recognise we must embrace

innovation, horizon scan and invest appropriately in R&D. Simultaneously continued capital

investment is required to progressively strengthen the portfolio at a proportional rate to meet the varying

demands across the network.

/

Mellor, R. et al. in review. Development of a Global Stability and Resilience Appraisal for Network Rail earthwork assets.

Quarterly Journal of Engineering Geology and Hydrogeology.

Merrylees, C. in review. Improving the understanding of weather drivers of earthwork failures along Britain’s rail network: a

data driven approach. Quarterly Journal of Engineering Geology and Hydrogeology.

Office of Rail Regulation, Arup & Network Rail. 2011. Part A Reporter mandate AO/007: review asset policy, stewardship and

management of structures. Final report – Review and benchmarking Available via hyperlink

Office of Rail Regulation, Arup & Network Rail. 2015. Part A Reporter mandate AO/049: review of updated earthworks asset

policy for CP5 years 3-5 Available via hyperlink

Power, C. et al. 2016. Development of an evidence-based geotechnical asset management policy for Network Rail, Great

Britain. Procedia Engineering 143: 726–733, Available via hyperlink

Presentations from 2017 Conference Ground Related Risk to Transportation Infrastructure, including keynote on “Strategic

geotechnical asset management challenges”, Available via hyperlink

4-May-18 58

Further Information

Network Rail Earthworks Technical

Strategy (left) will shortly be available

online, together with our challenge

statements that are published on our

website and are available via hyperlink

We are always keen to hear from the

supply chain to assist in the development

of ideas, solutions and products. Please

do get in touch and if your idea or

proposal sparks interest we will invite

you in to present to our engineers in

Milton Keynes R&D@networkrail.co.uk

/ 4-May-18 59

Thank you