Network Analysis/Critical Path Method (CPM)
Purpose and Scope: The VA requires the use of the Network Analysis System-CPM (Critical Path Method) on all major projects and / or other VA projects where the best interest of the Government will be served by its use. It is intended to:
- Obtain information and data that are needed by The VA Management, to identify, manage, and resolve potential project problems.
- Control documents, manage, and monitor job site progress.
- Establish realistic construction project duration(s).
VACPM System: The Network Analysis System (VACPM System) consists of the following:
- Graphic representation (CPM Network), demonstrating the logical sequence of the work and the time required for each of those work activities.
- The cost of each work activities for the purpose of making payments to the contractor and providing cost management information to the VA.
- Monthly update monitoring analysis.
- Project status reporting.
VACPM Network Diagram
The network diagram is utilized to describe as a standard activity-on-node network of events and is generally developed using the technique set forth in the current AGC publication CPM in Construction - A Manual for General Contractors. Project length is one of the most important cost considerations on any construction project. For a contractor, the major benefit of using CPM on a construction project is that the job can be built on paper to determine the shortest, most effective and profitable approach. The accuracy of the CPM schedule in obtaining this goal is dependent upon good network diagram logic and sequence.
Submission, Review and Approval of the Contractor’s CPM Diagram
The contractor is required to provide two (2) CPM submissions per the NAS section(s) of the specifications: (1) proposal for a CPM consultant and (2) complete final (day-1) network diagram. After the VA review and approval, these submittals become the approved project schedule. The payments for work performed can be made after satisfactory compliance with the CPM submissions is obtained.
The CPM Progress Updating
The CPM progress update shall be done monthly on a date mutually agreed upon by the contractor and the VA senior resident engineer. Also, the Look-Ahead Report should be marked up by the contractor and given to the resident engineer at least three work days prior to the progress update meeting so that it can be reviewed and verified. Actual start and finish/completion dates should be reported for each activity during the monthly updates as appropriate. Once mutual resolution of the issues and/or disagreements is reached, both parties sign the Look-Ahead Report and the appropriate distribution is then made.
Contract Changes and Time Extensions
CPM Time Analysis on Contract Changes: The effect that changes or delays have on a CPM schedule is determined by a comparison of the schedules before and after the delaying activities are incorporated into the CPM Network. Normally, the contractor is entitled to additional contract time if only the delayed scheduled completion is beyond the extended contract completion date.
CPM Analysis for Time Extensions: Delays to the project, due to strikes, weather, and other acts of God, or facts out of the control are usually the only scheduling problems that require an "after-the-fact" CPM analysis. Once work on the project resumes, the CPM analysis can be made to determine the delay impact to the schedule. The CPM procedure for developing and making a time extension analysis is the same as for any other type of delay.
Managing a construction project requires continuous oversight of the project, specifically through the cost and manpower loaded CPM schedule. Manpower and cash flow are two of the key elements, both of which must be consistently monitored to identify potential project slippage. The major causes of project slippage are:
- Delays due to changed work.
- Faulty Schedule Logic or unrealistic activity durations.
- Insufficient manpower.
- Contractor's failure to work on critical path activities.
Note: For more information on VACPM System, refer to the VA Technical Information Library (TIL).