Work breakdown structures are based on divide and rule policy. The total scope of the project is broken down into smaller manageable pieces known as work packages. Once developed, Work breakdown structures (WBS) are the focal point for project planning, scheduling, budgeting, monitoring and controlling. It is almost impossible to arrive at accurate estimates without good work breakdown structures. Incomplete or wrong work breakdown structures will lead to serious problems as the project progresses into the subsequent project phases.
In this blog post, we explain;
- The 10 characteristics of good quality work breakdown structures
- Steps to construct good work breakdown structures with desired quality levels
10 characteristics of good Work Breakdown Structures
- 8-80 guideline – In good quality work breakdown structures, almost all the work packages adhere to the 8-80 guideline. The 8-80 guideline states that the work packages must not be lesser than 8 hours of effort and not more than 80 hours of effort.
- 100% rule – They fully adhere to the 100% rule. The Work Breakdown Structures must cover 100% of the scope defined.
- Structure of WBS – Work breakdown structures convey the total scope of the project to the relevant stakeholders. Must be well presented, either as a tree structure or as a list structure.
- WBS dictionaries – Good work breakdown structures are supported by WBS dictionaries.
- Codification – Every work package is identified with a unique code. Good quality work breakdown structures are supported by well thought out codification schemes which supports monitoring and control of the project.
- Work package sizing – In good quality work breakdown structures, the Work packages must be shorter than the project’s reporting period
- Work package naming – Work packages are always named as Nouns.
- Team -There are always committed cross functional teams behind the development of good quality work breakdown structures.
- Progressive elaboration – Are developed progressively as the scope evolves.
- Project strategy development input – Aids the project team to develop the project’s strategy for execution
Let us inquire into the steps involved in developing good quality work breakdown structures which satisfy the above 10 criteria.
Steps to develop good Work Breakdown Structures (WBS) with good Quality
1. What is a Work Breakdown Structure?
Divide and rule is the philosophy behind developing the Work Breakdown Structures (WBS). Once the requirements are collected, and the scope is defined, then it is time to decompose the scope into a Work Breakdown Structure (WBS). Work Breakdown Structures are a deliverable-oriented grouping of work. They decompose the complete scope of the project into smaller manageable components known as Work Packages.
2. When is the work break down structures prepared?
The development of work breakdown starts immediately after the project’s scope is more or less finalized. The product of the project is decomposed into a Product Breakdown Structure (PBS). From the Product breakdown structure , the Work Breakdown Structure is developed.
Work Breakdown Structure is developed progressively. In reality, the Work Breakdown Structure evolves through the Scope definition and Product breakdown development. While developing the schedule, the work breakdown structure may get updated, which can get cascaded to the scope document as well.
3. Who prepares it?
For medium to large projects, multi-disciplinary knowledge is required to develop the Work Breakdown Structure. The Project manager is accountable for the development of the work breakdown structure with the help of a cross functional team.
4. How is it prepared?
4.1 Clarity of the scope and objectives of the project is mandatory
The first prerequisite to start the development of the Work Breakdown Structure is to have a high level of confidence and clarity on the project’s scope and objectives. If the scope definition is wrong that will be carried forward to the WBS and to the final deliverables.
4.2 Determine the Product Break Down Structure (PBS)
The product’s scope is decomposed into the major components of the final product. What are we building?. This question is answered by the PBS. The Product Breakdown Structure does not address the ‘How to build?’ part, which is taken care in the next step. Before moving on to the next step, let us take a look at the PBS for a new house;
There is nothing like a correct PBS. The Product Breakdown Structure must cover all the major deliverables of the project.
4.3 Determine the Work Packages
How are we going to build the product of the project?
As we saw in the previous paragraph, The Product Breakdown Structure (PBS) shows the major components of the product to be constructed. The Work Breakdown Structure (WBS) provides the answer to ‘How are we going to build it?’. Add to the PBS all the work that needs to be performed to build the product, and you get the Work Breakdown Structure.
Here is the Work Breakdown Structure for a new house;
Work packages are in the lowest level of the Work Breakdown Structure. There will not be any further levels of decomposition below the work package level.
From the example above;
‘1. SiteWork’ is not a work package as there is ‘1.1 Permissions’ below it. In this case ‘1.1 Permissions’ qualifies as a work package as there is no level below it.
‘2. Foundation’ is a work package, as there is nothing below it
3.1 and 3.2 are not work packages, as there are levels below them
3.1.1 to 3.1.11 are work packages
3.2.1 to 3.2.6 are work packages and so on.
Levels of WBS
How many levels should Work Breakdown Structures have ?.
There is no single correct answer to this question. The size and complexity of the project determine the number of levels in a WBS. The 8-80 rule proposed by PMI comes in very handy here. The 8-80 rule suggests that Work packages must be chunks of work that can be completed within 8 hours (1 day) to 80 hours (10 days). For very small projects the affinity of the work packages must be towards 8 hours and for large projects it must be towards 80 hours. Other criteria are that the work packages must fit into the reporting period of the project. If the work package sizing is not aligned with the reporting period, it will pose problems while reporting the project progress to other key stakeholders.
By the time the scope decomposition reaches levels 3 and above, the work packages will become granular enough to meet the criteria mentioned above. These are thumb rules, so exceptions are possible based on the need of the project and stakeholders.
The most commonly used formats for documenting the work breakdown structures are;
- Tree structures (shown above)
- List structures – are hierarchical textual representation of the work breakdown structures
4.4 WBS dictionaries
WBS dictionaries help to reduce ambiguity. WBS dictionaries provide additional information about the work package. Like;
- What are the predecessor activities?
- What are the successor activities?
- In order to prevent errors, a detailed description of the work to be performed is provided in the WBS dictionary
- Which are all the Standards to be followed ?
- Precautionary measures to be taken
- Instructions to deal with special situations etc
5. Conclusion
As the project gets progressively elaborated, the project scope gets clearer. Once enough scope clarity is achieved, the product breakdown structure (PBS) is developed. The Product Breakdown Structure is superimposed with the activities required to build the product of the project. This step results in the work breakdown structure.
Good work breakdown structures have the following 10 characteristics;
- How do we decide on the sizing of the work packages?. 8-80 comes in very handy. 8-80 rule states that work packages must be between eight hours and eighty hours chunks of work. If the projects are big, then work packages can be around 80 hour chunks of work. For small projects the work packages can be around 8 hours, or it could be anything between 8 hours and 80 hours. Smaller projects having very large work packages as well as very large projects having very small work packages will affect project progress monitoring.
- Work breakdown structures adhere to the 100% rule. The Work Breakdown Structures must cover 100% of the scope defined. If something is missed out in the final work breakdown structure, that will be missing in the final deliverable of the project.
- Some project stakeholders like graphical reports where as others prefer textual reports. Work breakdown structures convey the total scope of the project to the relevant stakeholders, hence must be well presented. WBS can be presented either as a tree structure or as a list structure, depending on the preference of the stakeholders.
- Work packages must communicate the entire scope of work contained in the work package in such a manner that there is no ambiguity for the person who is really executing the work. WBS dictionaries help to provide additional information about the work specified in the work package. Good work breakdown structures are supported by WBS dictionaries. Typical WBS dictionaries contain;
- Detailed description of the work to be performed
- Predecessor activities
- Successor activities
- Technical specifications to be followed
- Quality goals to be achieved
- Reference document references etc
- Every work package is identified with a unique code. Good quality work breakdown structures are supported by well thought out codification schemes which supports monitoring and control of the project.
- In good quality work breakdown structures, the Work packages must be shorter than the project’s reporting period
- Nouns are used to name work packages
- There are always committed cross functional teams behind the development of good quality work breakdown structures.
- Are developed progressively as the scope evolves.
- Aids the project team to develop the project’s strategy for execution
Emerging trends in Work Packaging
Advanced Work Packages and Work face planning
Advanced Work Packaging provides a structure for focused execution planning that is directed at the construction workface. It is a process that reduces unproductive, non-value added time. A key requirement of this process is a collaboration between construction and engineering during the engineering planning phase. This collaboration ensures that the project is designed with a sequence that supports construction and that the supply chain is sequenced accordingly.
Advance Work Packaging (AWP) mandates three more classification for work packaging;
- Engineering Work Packages (EWP) – An engineering work package is an engineering deliverable that is used to develop Construction Work Packages. An EWP defines the scope of work to support construction in the form of drawings, procurement deliverables, and specifications.
- Construction Work Packages (CWP) – A construction work package is an executable construction deliverable that defines in detail a specific scope of work and should include a budget and schedule that can be compared with actual performance. The scope of work is such that it does not overlap another CWP and can be used as a scoping document for Requests for Proposal and Contracts.
- Installation Work Packages (IWP) – An installation work package is a detailed execution plan that ensures all elements necessary to complete the scope of the IWP are organized and delivered before work is started to enable craft persons to perform quality work in a safe, effective and efficient manner. Generally the scope of work associated with the IWP should be small enough that it could be completed by a single foremen team in a one or two week time frame.
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