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Organization Breakdown Structure (OBS) can be defined as a framework or hierarchical representation of different roles within an organization, their responsibilities, and accountability. OBS can be implemented as a tool to manage the authorized work defined within the scope statement of the project.

Construction projects involve a series of complex activities and decisions that require expertise along with clearly defined responsibilities. Several entities serve different purposes in construction projects and therefore having an OBS for clear allocation of roles is necessary. These roles and responsibilities must be based on the primary objectives of the project which mostly revolve around a business motive.
Contents:
Structure of OBS
OBS is an illustration of the method for the arrangement of organization and how these arrangements would report issues pertaining to the construction project. OBS is a mere reflection of an organization based on the functions of project stakeholders.
A construction project is usually broken into different segments where each segment is composed of several activities. These segments are called work breakdown structure (WBS) while these activities are usually termed as work packages.
The OBS shares a deep relationship with WBS. OBS defines which entity would be responsible for the completion of a certain segment of WBS. This process is usually aided by the technique of Responsibility Assignment Matrix (RAM). This also helps to define the scope of work.
The structure is purely based on the objectives of the project while considering the facility of subcontractors, staff, architectural and technical staff. Usually, the structure of OBS is prepared by the project manager and it may contain modifications based on the size, complexity, and scope of the project.

Responsibility Assignment Matrix (RAM)
The technique of RAM is implemented in complex projects to assign different project members their respective activities or work packages. RAM is the visualization of the interaction between tasks that are needed to be completed for objectives and members of the project team. Different team members possess a different set of skills and they get assigned work based on their working capabilities or area of expertise.
The figure given below depicts a standard RAM, although there is room for variations based on variations in the project.

Development of an Effective OBS
An effective OBS is one that clearly defines the roles of the different entities involved considering the scope, stakeholders, and objectives of the construction project. Usually, it stabilizes the quality standard, reduces cost, and aids in finishing the project in time. The following steps must be considered for the development of an effective OBS.
- First of all, the scope statement should be prepared and a management environment should be established.
- All the stakeholders that can influence the project must be identified.
- Once the project scope statement has been defined along with the objectives of the project, the requirements must be recorded. These requirements would serve as the basis for the work package establishment. All the activities needed to be done are identified. This serves as the basis for a work breakdown structure.
- Once the WBS has been created, different project members are assigned responsibilities based on RAM.
- Thus, unification of WBS is done with OBS.
Benefits of OBS
- Construction project management is mainly concerned with constraints inflicted over the project, like scope, cost, and time restraint. These constraints can be easily dealt with by preparing a perfect OBS. Organization Breakdown Structure helps us to organize human resources in an efficient manner. This efficient management of assets would help in understanding the work requirements.
- Once the OBS has been established, scheduling becomes an easy task for the management team. The information about resource allocation is present in OBS and an effort estimate is also made, resulting in less time consumption in the process of scheduling.
- The entire scope of the project can be visualized once the unification of WBS and OBS has been done. The entire scope of work can be prepared with the aid of WBS and OBS.
- Construction projects are liable to mishaps and uncertainties. OBS can be used to identify who is accountable for certain risks and hazards.
- Furthermore, OBS defines the link of communication between different members of the project. This establishes the communication method that can be used for good execution and management of the construction project.
- OBS makes sure that all the milestones are completed and no deliverable is overdue or forgotten.
OBS as a Management Tool
Organization Breakdown Structure in construction projects has a significant role due to its effective management application. In complex projects, different phases may overlap, creating a situation where it is hard to identify the team members that are needed for performing different activities.
This can give rise to uncertainties in a project. If every member in the team is aware of their responsibilities and roles, they can work efficiently. Most of the safety and hazard guides recommend the use of OBS to define and implement construction strategies.
OBS forms the basis for many other breakdown structures that can be used throughout the various cycles of a construction project. These include cost breakdown structure, resource breakdown structure, risk breakdown structure, and feature breakdown structure.
Conclusion
In short, there are many management tools that are implemented for achieving certain objectives within a construction project and OBS does add to these tools.
Large organizations tend to define their structure and implement it for all the projects. It is an iterative process. On the other hand, some of the small project teams that are disbanded after each project have to establish their OBS separately for the next project.
OBS would be beneficial in the management and allocation of the resources, and the organization of team members. It makes sure all the activities are completed on time and no objective of the project is compromised.
FAQs
Organization Breakdown Structure (OBS) can be defined as a framework or hierarchical representation of different roles within an organization, their responsibilities, and accountability. OBS can be implemented as a tool to manage the authorized work defined within the scope statement of the project.
The structure of OBS is purely based on the objectives of the project while considering the facility of subcontractors, staff, architectural and technical staff. Usually, the structure of OBS is prepared by the project manager and it may contain modifications based on the size, complexity, and scope of the project.
RAM is the visualization of the interaction between tasks that are needed to be completed for objectives and members of the project team.
Read More
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How to Plan a Construction Project using Work Breakdown Structure? [PDF]