Managing construction risk using

the Observational Method

Dr Jason Le Masurier

Department of Civil Engineering

Contents

Geotechnical engineering risk The Observational Method Research project Case studies Systems to support the OM process Putting it into practice

Geotechnical Engineering

Boreholes

Temporary steel props

Attempts to eliminate uncertaintycan be wasteful…

…on the other hand

Predefined design Design Construct

Redesign

‘Fire fighting’

OK for predictable / low uncertainty cases

Otherwise:

Approaches to geotechnical design

1

Traditional construction procurement encourages the predefined design approach Linear and fragmented procurement route Lowest price bidding Desire to eliminate uncertainty / risk

There is an alternative…

The Observational Method

2 The Observational Method

Information and knowledge of

the ground

Design for most probable

Design contingencies for most

unfavourable

Observe -monitor

performance

Construct next stage

Design - review & improve further or use contingencies

Select

performance

indicators and

set triggers

Information and knowledgeof the ground

Perception

Action Reflection

Human nature

Perceived need

Implement design

Design solution

Construction Best Practice ??

Perceived need

Implement design

Design solution

‘Traditional’ construction practice

There are benefits in being ‘ Loopy ’

Monitor / observe

Construct Design (review)

Observational Method

See what happens

Think about it

Driving a car

Do something /nothing

Risk and opportunity

Final cost based on predefined design

Estimated cost

Cum

ulat

ive

Des

ign

cost

Cum

ulat

ive

Con

stru

ctio

n co

st

OM – minimum cost option

--- Predefined

OM design

Changing perceptions of cost as a project develops

after Muir Wood, 2000

Research project – University of Bristol‘Geotechnical innovation through observation’

Research funded by the Partners in Innovation initiative and supported by 12 industrial partner organisations.

The key objectives were: to enhance robustness of the Observational Method in

practice through systems thinking and process modelling;

to demonstrate the Observational Method as a special case of a generic approach to uncertainty management;

apply the process modelling methodology to a live construction project.

Action research

Case study research

Grounded theory

Grounded theory

Brainstorming workshop

Working in industry

Interviewing project team members

Interviewing domain experts

Research methodology

Technology Transfer Secondment

Case studies

New Hong Kong Airport Platform M6 Motorway, Scotland Limehouse Link, London Heathrow Express Tunnels, London

Chek Lap Kok Airport Platform – managing settlement uncertainty

Chek Lap Kok Airport Platform – installation levels procedure

M6 Motorway Construction, Scotland

M6 Motorway Construction – soil nailing

Grouting facility to mitigate settlement risk

Limehouse Link, London – eliminating temporary support on a 1.7km cut and cover tunnel

Heathrow Express Tunnels – NATM construction

Heathrow Express Tunnels – the morning after

Monitor / observe

Construct Design (review)

Enquiry findings

‘Organisations and groups of organisations have multiple defences to prevent incidents. In the construction industry these defences can be influenced by the contractual relationships…This has the advantage of providing some redundancy and diversity in the defences against failure but it can also provide the opportunity for misunderstandings and simultaneous failures where there is uncertainty about the respective roles and responsibilities of the parties.

• Cooperative culture • Coordinated teams • Common objectives• Communicate efficiently• Clarity over responsibilities• Creative thinking• Continuous improvement

‘C’ for success of Observational Method

Identifying next stage

construction

Monitoring

Reviewing values from monitoring

Using emergency

plan

Deciding on action

Taking extra readings

Excavating next stage

Reviewing conditions

Using contingency

plan

Agreeing

Main contractor

Sub contractor

Geotech. designer

Geotech. control Monitor

GREEN

AMBER

RED

Surveying

Designing the process

Parameter Moderately Conservative

based on design codes

Most Probable

based on experience

Reference

Made Ground / = 25 / = 38 OAP - Broadgate

Taplow Gravel / = 36 / = 40 Lehane et al

London Clay / = 23 c/ = 0 / = 24 c/ = 10kPa OAP, Cross Rail

Lambeth Clay / = 23 c/ = 0 / = 28 c/ = 25kPa OAP, Cross Rail

Water Pressure in Taplow Gravel +7.5mOD None Geotechnical Report

Minimum Equivalent Fluid Pressure applied from GL None Observations

Softening Passive soil None Observations - OAP Horseferry Road

Surcharge 20kPa 20kPa (Perm) 10kPa (Temp)

-

Overdig 0.5m None -

Undrained Shear Strength London Clay

70+7.5z*kPa

+5.5mOD - 11.0mOD 112+5.19z kPa *

-11.0mOD - 17.5mOD 200kPa

-17.5mOD - 29.2mOD 400kPa

Results - see Justification Report

Undrained Shear Strength Lambeth Clay 300kPa 400kPa Results - see Justification Report

Stiffness of Clay (Eu) 1000cu 1500cu Back-analysis

Empirical approach to design

Alternative construction sequencesOriginal design construction sequence

Observational Method design construction sequence

1 2

321

43

Secant pile wall

Existing basement

Permanent floor slabs / props

Arup (GIE) HBG McGee Arup (OMR) Soil Instruments Ltd

OMR

IMS

Project Manager

Project Manager

Project Manager

Identifying next stage of

construction

Reviewing values from monitoring

Reviewing conditions

Deciding on action

GREEN Processes

AMBER Processes

RED Processes

Reviewing values from monitoring

Reviewing values from monitoring

Section Engineer

Monitoring primary system

Surveyor

Project Manager

Construction Manager

Monitoring supplementary

Implementing contingency

plansConstruction

Manager

Byrne Bros.

Construction Manager

Monitoring supplementary

Monitoring supplementary

Monitoring primary system

Monitoring primary system

GIE

Designing the process - responsibilities

Client satisfaction

Hard Key Performance Indicators SoftTime Cost Functionality People

% complete % budgetspent

Wall deflection Settlement

Efficiency ofcommunicationCooperation of team

Material wastage

Feedback

Continuous im

provement

and learning

Client Designer Sub-contractorContractorChecking

designDesigning

works

Identifyingnext stage

Constructingnext stage

MonitoringReviewingdesign

Checkingdesign 2

Decidingactions

Level 2

Level 1

Level 3

Level 4

Shared objectives

Proj

ect p

rogr

essi

on

Monitoring

Action

Client satisfaction

Hard Key Performance Indicators SoftTime Cost Functionality People

% complete % budgetspent

Wall deflection Settlement

Efficiency ofcommunicationCooperation of team

Material wastage

FeedbackBenchmarking

Integrated processes and teams

Value Management

Partnering

Continuous im

provement

and learning

Client Designer Sub-contractorContractorChecking

designDesigning

works

Identifyingnext stage

Constructingnext stage

MonitoringReviewingdesign

Checkingdesign 2

Decidingactions

Level 2

Level 1

Level 3

Level 4

ObservationalEngineering

Shared objectives

ConclusionThe Observational Method:

has a track record in successfully managing ground uncertainties – minimising risk and maximising opportunity

thrives under collaborative project relationships requires explicit, integrated project processes and

clearly defined responsibilities is an example of a generic approach to managing

project uncertainty that can be applied holistically

Conclusion

“ If a man will begin with certainties he shall end with doubts; but if he will be content to begin with doubts, he shall end in certainties”

Advancement of Learning, Francis Bacon

Observe / monitor ‘hard’ KPIs

Construct next stage Review

PRODUCT design - improve / use contingencies

Observe / monitor ‘soft’ KPIs

DO IT Review PROCESS design - improve / use contingencies

Why do we want this project?

DO VM

... for strategic planning - WHY

DO VM...

… for PROCESS design - what, who, how, where, when

ContinuousVE

DO VE…initial design of

PRODUCT

...design the PROCESS

How will we achieve it? ...

…improved design of PRODUCT

ContinuousVM

OMloops

© Jason Le Masurier, 1999