Part 1 – Technical Assurance Framework

Evidence-Based System Assurance

System Assurance uses a risk-based approach which is applied from preliminary scheme design activities, through the project lifecycle and into operation. System Assurance works interactively with each Contractor’s during the development of a system in order to provide compliance evidence and arguments timely. The documentation framework is needed to support the Contractor’s practices and to provide confidence to Crossrail. The assurance is deemed to be progressive. Any highlighted deficiencies in the Contractor’s practices or in the evolving evidence are addressed before progressing enabling compliance to the approvals gates for the next lifecycle phase(s). The approach to System Assurance adopted in Crossrail is non-prescriptive in terms of the development process. The assurance requirements are defined such that they can just as effectively be applied to existing systems and to various development lifecycles, subject only to the appropriate evidence being available.

Contractors must address the discipline of System Assurance throughout the lifecycle in terms of both their understanding and approach. If some areas of a project proceed with only a limited awareness of assurance, this will pose an increased risk of time delay, cost overrun and lost performance to the project. Raising awareness and understanding of the importance of System Assurance at all levels in the organisation and across all areas of the project is key to minimising this risk. It is essential that a common framework is established at an early stage in the design process that is both rigorous and consistent across all interfaces.

In addition to the above, Crossrail also undertakes assurance activities to supplement or validate the work of the Contractor. To facilitate these activities the Contractor shall provide access to his facilities, personnel and documentation.

One of the principles that apply to evidence-based System Assurance is that the “burden of proof” rests with the Contractor. It is the Contractor’s responsibility not only to provide assurance arguments as stated in this document but also to show how that evidence supports the associated argument. As the approach to System Assurance is as non-prescriptive as possible, it is the Contractor’s responsibility to justify what he does. Interpretation of terms such as “adequate”, “acceptable” and “appropriate” is left to the Contractor’s judgement initially. However, Crossrail’s interpretation shall prevail whenever the Contractor’s interpretation presents an unacceptable risk to the project. Furthermore, all evidence must be documented in a way that allows it to be inspected. Activities which are undertaken during the development which do not lead to documented output cannot provide any valid form of evidence unless specific alternative forms of evidence are proposed by the Contractor and agreed by the Crossrail System Assurance Manager.

The System Assurance framework adopted for MEP installations at stations shafts and portals is presented in Figure 1. The main goal of System Assurance is to demonstrate that the project and the development of individual systems will be successful. In fulfilling this goal, the system should meet the specified user requirements and is fit for its intended purpose. The system should be ready to go into service on time and within budget. This viewpoint is addressed through the Process Assurance and People Assurance requirements.

Figure 1 – System Assurance Framework

Basis of Assurance

Product Assurance addresses the adequacy of the system by ensuring that a complete and consistent set of requirements are specified and that these requirements are fully satisfied in the delivered system. Demonstrate that system development provides the specified functionality and is available on time, within budget and meets the needs of the project.

Product Assurance is required for all systems irrespective of their previous history and maturity. Arguments and evidence may be obtained from an appropriate combination of field-service experience of existing (or sufficiently similar) products, analysis of the system, and testing of the system.

Process Assurance ensures that the Supplier has an acceptable set of management processes in place to support the development and monitors adherence to these processes.
Process Assurance is required to some extent for all systems but the scope of its application will depend on both the assessed development risk that the system presents to the project timescales and/or costs. Arguments and evidence shall be obtained from the processes used in the development of the system.

People Assurance ensures that all Supplier staff are competent to undertake the Product and Process Assurance tasks for which they are responsible. People Assurance is required for all systems irrespective of their previous history and maturity. Arguments and evidence shall be obtained from the processes used in the development of the project.
This paper focuses on the product (and service) aspects of the project. Process and people aspects of the projects are dealt with in the quality assurance regime.

Evidence Level

For each assurance objective and corresponding lower-level arguments, evidence is required in two forms:

• Direct Evidence- The term for an item of evidence that is a direct output of undertaking an assessment, development or testing activity. The existence of this evidence provides confidence that the activity has taken place. Examples of Direct Evidence are requirements specifications; design documentation; and test specifications, plans and results.
• Backing Evidence- The term used for an item of evidence that provides confidence that an item of Direct Evidence is credible, soundly based and trustworthy. It is based usually on the adequacy and competent application of the process which gave rise to the Direct Evidence. Examples of Backing Evidence are evidence of the effective review of requirements, design, testing and commissioning documentation; results of verification activities used to demonstrate the adequacy of the decomposition of the design; and confirmation that staff have been subject to competency reviews.

Technical Assurance

Within the range of assurance requirement covered by the Integrated Assurance and Approval Plan (IAAP)[1] , Technical Assurance covers the technical functionalities of the project deliverables. In the context of MEP installations in stations shafts and portals, it refers to the performance of the installations and their interaction with other railways system installations. To put the system at work, there is a need to assign a technical authority to oversee the successfully implementation of technical assurance plan. The Chief Engineer Group is the Technical Authority for Crossrail.

Part 2 of this paper highlights the scope of assurance evidence required for the MEP installations at the Crossrail stations shafts and portals. The documentation framework presented help illustrate the implementation of technical assurance plan for Crossrail.

Part 2 – Technical Assurance Evidence for MEP Plant in Stations Shafts and Portals

In Part 2 of this paper, the mechanical, electrical and public heath (MEP) installations at stations, shafts and portals are used to illustrate how the Crossrail line wide technical assurance regime is put at work.

Figure 2 describes how the technical assurance data are captured and assimilated during the design, construction and verification/ validation stages in the project life cycle. Throughout these stages, the Contractors are required to provide assurance evidence in a progressive manner to demonstrate compliance with performance requirements as set out in the project brief. These documents are kept electronically in the centralized ‘eB’ documentation system under the respective category for ease of retrieval and cataloguing. In general, there are three main categories of assurance documents:

• Technical related assurance documents
• Process or procedure related assurance documents
• Verification and Validation related documents

Figure 2 – Flow diagram illustrating how assurance data are captured
and assimilated in the project life cycle

Table 1 provides the range of assurance evidence that Crossrail will expect from the Contractors for the MEP installations.

Table 1– Categories of assurance evidences to be provided for MEP installations

The above exercise generates a large volume of assurance evidence in the assurance database. While they provide valuable information on technical and procedural compliance with project requirements, not all information are relevant to the handover deliverables of the project. Towards the handing over of MEP installations, there is a need to present technical assurance case for MEP installations. To facilitate this, the relevant assurance evidences are identified and grouped into the following three categories:

1. Lead Assurance Documents.
2. Compliance Evidence.
3. Supporting Quality Documents.

The following sections provide in further details what is contained in the three classes documents for mechanical, electrical and public health installations for stations, shafts and portals in Crossrail.

Key success factors for an effective technical assurance regime are:

• A good mix between procedural and technical compliance evidence
• A good grasp of the pertinent assurance requirements in particular statutory requirements and industry codes
• A structured line wide documentation system
• Coherent acceptance criteria line wide.

Lead Assurance Documents

The lead assurance documents will provide evidence to which confirm that the prescribed specific performance criteria are met. The lead assurance documents are reviewed and endorsed by the assigned assurance engineer(s) of Crossrail for the respective engineering disciplines. A list of the lead documents for the MEP installations is shown in Table 2.

Table 2– List of Lead Assurance Documents

Compliance Certificates

Table 3 provides a list of compliance certificates that are required for the MEP installations to satisfy statutory requirements. The set of certificates has to be complete, adequate and suitable for the purposes of enabling Crossrail to obtain authorisation to enter into passenger service.

Table 3– List of Assurance Certificates

Supporting Quality Documents

Supporting quality documents or backing evidence (as sets out in Table 4) is the part of the database that will supply the evidence for the lead assurance documents and compliance certificates. Each work package will have its own list of documents pertaining to the nature of work, work scope and complexity.

Table 4– List of Supporting Documents

Conclusion

An effective and systematic approach to capture and assimilate assurance data is an important part of project management procedure to demonstrate compliance with project requirements. Maintaining a consistent and coherent documentation framework is particularly a challenge to multi-disciplinary project where a large number of discrete work packages are working in tandem towards a set of common performance requirements. In this paper, the data processing framework developed for MEP installation is used to illustrate how the technical assurance regime of Crossrail is put to work.

Ability of the technical assurance regime to maintain a good collection of documents that covers all the pertinent assurance requirements is of paramount importance in this context.

References

[1] HM Treasury, Integrated Assurance & Approval Strategy and Integrated Assurance & Approval Plans- A guide to implementing integrated assurance and approvals, Cabinet Office, 2011
[2] A Design Framework for Building Services, 3rd edition BSRIA, 2012