Construction Execution Model
A “Project” can be thought of as the change in physical state within a given space over a defined period of time. In construction, these boundaries are expressed in the construction documents consisting of agreements, general conditions, specifications and drawings. Each contribute information needed to convey the intent of the owner as to the final outcome of the project. They are to be consider as a whole and in themselves do not imply any breakdown of the work for the purposes of execution. The whole of the work is commonly defined as the “Scope of Work”.
It is the general contractors responsibility to break the scope of work into smaller parts that define who, what and when of the execution of the work. He is responsible to understand all constraints that effect the installation of the work and to sequence the work appropriately ensuring all requirements are completed on time and the work is installed as per the contract documents.
The Construction Execution Model is a logical framework that supports the development of the scope of work at the correct level of granularity at the right time that satisfies each control process and to identify all requirements that effect each part.
There are three fundamental elements to the model – the “Work Item”, “Constraint” and “Dependency”. Together they define the entire scope of the work, who is responsible to furnish and install it and when it will be installed complete ready for its intended use.
Construction Execution Model (CEM) - Fundamental Elements
Work Item – A representation of the physical action and constructed result of a portion of the scope of work. It is the end result after all labor, material and equipment have been expended to produce a portion of the work ready for its intended use.
Constraint - Requirement that must be complete prior to the fabrication, delivery, installation and final acceptance of work items.
Dependency - Relationship defined between two or more work items and or constraints. They represent the sequence work items must be installed based on physical and procedural constraints, occupancy requirements and other factors that affect the progress of the work.