TC206 Observational Method

Observational Method

Host Member Society: United Kingdom

Short name: Observationall Method (TC206) - Terms of Reference - approved

Contact: TC206 Secretary, Prof. B.K. Maheshwari, E-mail: [email protected]

TC-206 External Website: Observational Method

Objective 1 - Develop and disseminate knowledge and practice on Interactive Design (ID) .

The term “Interactive Design” (ID) is currently undefined.  It appears to be the same as the “The Observational Method” (OM), which has a body of references and is already referred to in guides and codes, eg, Eurocodes and ISO.

The TC members will debate the (if any) differences between “Interactive Design” and “The Observational Method”.  The outcome will be recommended for further use.  This might also mean a possible change of the TC206 title if the TC members feel the need for that.  The current working approach for the TC206 will be to assume ID is the same as OM.

An over-arching theme for the TC206 would be to develop the breadth of OM applications in different branches of Civil Engineering as a method of dealing with risk and uncertainty.  The goal is to develop a common simple framework and definition across Civil Engineering.

Objective 2 – Establish guidelines and technical recommendations within ID/OM framework

Currently the Eurocode is the most advanced standard dealing with the Observational Method.  This should be extended to other codes and tested on projects.

Part of this objective is to introduce OM into parallel codes and disciplines, such as Tunnelling and Environmental Engineering.  Key features to address are the large uncertainties in design parameters, modelling and construction methods.  Instrumentation and data handling are equally important.

Objective 3 – Play an active role in conferences organised by ISSMGE

TC206 can contribute to sessions or workshops at conferences organised by other ISSMGE committees.  TC206 does not intend to organise separate conferences.  The aim is to interact in the conferences to advance a clear ID / OM process.  The objective is to reduce the use of the “trial and error” approach, which is potentially dangerous.

ISSMGE case history conferences have much in common with OM.  The back analysis or inverse analysis of case histories is key to assessing the most probable parameters.  There is a need to promote papers which rigorously apply the OM framework.  Contingency plans and mitigation measures are important to control safety.  The TC206 will promote and encourage such papers.

Objective 4 - Interact with industry and overlapping groups working with ID/OM

One of the big barriers to OM is how to implement the OM into civil engineering contracts.  It is important to identify parallel disciplines which use the OM process but have a different frameworks and terminology.  Tunnelling and rock mechanics are examples.  What lessons can be learnt exchanging different views and approaches?

To develop the OM process, it is important to engage with other TC’s regarding: -

  • Civil engineering applications that are appropriate for OM.
  • Site investigations and soil parameters - where a wide range of uncertainty exists.
  • Numerical modelling and its limitations – links with back analysis assumptions.
  • Instrumentation systems – The accuracy is important.
  • Data handling, statistics and risk/safety assessment – Real time back analysis or inverse analysis is increasing. 
  • The reassessment of conventional designs based on the back analysed most probable parameters. Establish the degree of conservatism and potential for material reduction.
  • The process of defining trigger values and contingency plans should be developed.
  • The contractual framework to use the OM is important to establish.

# Type Full Name Country
1 Chair Duncan Nicholson United Kingdom
2 Vice Chair Mandy Korff Netherlands
3 Secretary B.K. Maheshwari India
4 Nominated by TC Chair Ying Chen United Kingdom
5 Nominated Member Paweł Popielski Poland
6 Corresponding Member Fadi Haddad Germany
7 Nominated Member Christopher Menkiti United Kingdom
8 Nominated Member David Zhang Australia
9 Nominated Member Johan Spross Sweden
10 Nominated Member Tomasz Godlewski Poland
11 Corresponding Member Jinsong Huang Australia
12 Corresponding Member Andrew Ridley United Kingdom
13 Nominated Member Franz Tschuchnigg Austria
14 Nominated Member Miguel Conceição Portugal
15 Nominated Member Ayfer Erken Turkey
16 Corresponding Member Leen De Vos Belgium
17 Nominated Member Mehmet Berilgen Turkey
18 Corresponding Member Aliasger Haiderali United Kingdom
19 Nominated Member GUSTAVO ROCHA VIANNA Brazil
20 Nominated Member Habib Shahnazari Iran
21 Nominated Member Priyanka Ghosh India
22 Nominated Member Noel Huybrechts Belgium
23 Nominated Member Zhiguo Yan China
24 Corresponding Member Gavin Toh Hong Kong Special Administrative Region
25 Corresponding Member Augus Maxwell Hong Kong Special Administrative Region
26 Corresponding Member James Sze Hong Kong Special Administrative Region
27 Nominated Member Tara Wood Sweden
28 Nominated Member Christian Moormann Germany
29 Corresponding Member Amit Srivastava India
30 Corresponding Member Ki-Tae Chang South Korea
31 Nominated Member Calogero Valore Italy
32 Nominated Member Sebastiano Rampello Italy
33 Nominated Member Umur Salih OKYAY France
34 Nominated Member Tony O'Brien United Kingdom

The following “planned activities” are proposed by the TC206:-

  1. Contact TC members  (Objective 1) - The TC Members will write short CV’s summarising their OM experience and papers they have written.  The TC will then:-
    1. Identify gaps in the TC skill base and identify new members.
    2. Debate the difference in terminology between “Interactive Design” and “Observational Method” in (two) conference calls with the members.
    3. Identify a TC secretary from outside Europe with OM experience.

The timeframe for this is 3 months

  1. Establish Guidelines and Standards  (Objective 2) – Review the current use of OM in guides and design specifications.  

A developing area is real time back analysis using Bayesian methods to automate the redesign process.  Procedures need to be developed and tested.


A reference list and comparisons will be made.  The time frame for this is 6 months and parallels Eurocode updates.


  1. Conference Organised by ISSMGE  (Objective 3) – The OM is unlikely to warrant a conference by itself.  However, OM fits well with other ISSMGE conferences which have a large component of back analysis.  The following is planned:-
    1. Present at the ISSMGE Conf Sydney (Sept 2021) on the changes planned for the TC.
    2. Promote a clear framework and design process to be used with OM. 
    3. Organise sessions / participate in conferences on back analysis in geotechnics, including soil parameter assessment leading to most probable and characteristic parameters, tunnelling, environmental geotechnics, instrumentation, risk assessment, statistics and risk. 


  1. Interaction with Industry and other TC’s  (Objective 4) – To improve interaction with industry the TC206 needs to interact with construction contracts.  This will require contractor and client input.  The design and build contracts are possibly the easiest way to interact using value engineering clauses.  Initially the TC206 will encourage experienced contractors to join TC206.  The papers will be written to define contract options for OM input.

The Objective 4 identifies some of the other TC’s to interact with.The Chair/members of TC206 are individually interacting with the relevant TC’s and report back to the whole TC. From those contacts a proposal for a joint meeting is developed taking place at a ISSMGE conference.


The deliverables include:-

Objective 1 deliverables - An active TC206 group and clarification on ID / OM with a web site. – 3 months

Objective 2 deliverables – A coordinated approach to OM through different guides and codes.  The redrafting of the Eurocode is in progress.  The OM aspects will be disseminated - 6 months.

Objective 3 deliverable - Joint ISSMGE Conferences with other TC particularly on back analysis. - The ISSMGE 2021 will be a key target to link with other TC’s.

Objective 4 deliverable – A contractual framework for the use of OM by industry.  The first step in to identify key contractors and clients.  3 months – a contractual framework would take about a year.

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