, Considerations for Identifying and
Analyzing the Critical Path
Ronald J. Rider, MBA
Table of Contents
1. INTRODUCTION ............................................................................................................................... 1
2. THE CRITICAL PATH DEFINED .................................................................................................. 2
3. IS THE CRITICAL PATH VALID? ................................................................................................. 5
4. STEPS TO CONSIDER FOR IDENTIFYING THE CRITICAL PATH ...................................... 9
5. CONCLUSIONS ............................................................................................................................... 16
List of Tables
Table 3-1 Schedule Quality and Deficiency Check Examples .................................................................. 7
List of Figures
Figure 2-1 Single and Multiple Critical Path Examples ............................................................................. 3
Figure 2-2 Critical Path Influenced by Constraint Example ....................................................................... 4
Figure 3-1 Sample Critical and Near-Critical Path Bar Chart Sort by Early Start Dates ............................ 6
Figure 4-1 P6 Menu Items to Create Critical and Near-Critical Path Codes ............................................ 10
Figure 4-2 Defined Critical and Near-Critical Path Code Menu............................................................... 11
Figure 4-3 Identify and Code Latest Finishing Activity Example ............................................................ 12
Figure 4-4 Identification of Driving Predecessors from Activity A9999 ................................................. 13
Figure 4-5 P6 Critical Path Grouping and Summarization Example ........................................................ 14
Figure 4-6 Final Critical Path Summary Example .................................................................................... 14
, Considerations for Identifying and
Analyzing the Critical Path
1. INTRODUCTION
The primary purpose of the time management function for a project is to plan, schedule, control,
and monitor the timely completion of the project’s scope of work. The standard method used
throughout the construction industry is to apply the Critical Path Method (CPM) scheduling
technique. The CPM scheduling technique is utilized by project management to plan, sequence,
forecast, and resource level the start and finish of work packages or schedule activities.
The all-important analysis tool provided by the CPM scheduling technique is the ability to
determine the critical activities that comprise the critical path. The critical path represents the
longest path or overall sequence of tasks and milestones that determine the project’s overall
duration. Activities not on the critical path will have some degree of float or slack time; activities
with available float or slack time can be delayed by the number float or slack days without
delaying the project’s overall finish date.
Project stakeholders must know, with a high degree of certainty, what the forecasted critical path is
in order to make sound and informed decisions relative planning the remaining work, applying
resources, dealing with potential delays, or accelerating portions of the project scope. CPM
scheduling programs allow users to select the activities that are considered to be on the critical
and/or near-critical paths by filtering the schedule data based on the longest path or low float value
criteria. The critical path and near-critical path output is typically in bar chart format or in tabular
report format.
Unfortunately, for large and complex engineering, procurement, and construction (EPC) projects,
the ability to quickly and accurately identify, summarize, and evaluate the critical path and near-
critical paths can prove difficult. It is not unusual for large EPC projects to contain multiple
process areas represented by tens of thousands of schedule activities, which makes identifying the
critical path and near-critical paths a burdensome endeavor. Further, the user is at the mercy of the
CPM scheduling program in terms of how the output of the schedule data is presented. In addition,
any deficiencies in the CPM model such as open-end activities and overuse of constraints further
complicate and muddle the process.
Therefore, it is up to the schedule analyst to use the confines within the CPM scheduling program
to better organize the schedule data in a format that the project participants can understand. The
purpose of this article is to discuss some of the challenges faced and steps to consider when
identifying and analyzing the critical and near-critical paths.
, Considerations for Identifying and
Analyzing the Critical Path
2. THE CRITICAL PATH DEFINED
The critical path is generically defined as the longest continuous path of activities, from the
progress date or data date to the final completion activity, which determines the overall duration
for a project. The activities that typically comprise the critical path are those activities with the
least amount of total float (i.e., zero or negative total float values). An activity on the critical path
is planned to not be started or completed until its logical predecessor activity or activities have
started or completed. If a critical path activity is delayed by one or many days, then any successor
activities including the project’s final completion activity will be delayed unless mitigations are
taken to recover the delay.
The following are two scenarios among many used to explain the rationale behind adopting a
certain critical path in a given situation:
a) Scenario No. 1 – A contractor may develop a critical path based on the
calculated result of the planned network logic and estimated activity durations
and other milestones included in the schedule; or
b) Scenario No. 2 – A contractor may develop a critical path based on the
collaborative input from the project manager, superintendent, subcontractors,
and/or others to force the critical path to go through certain activities that those
experienced people are satisfied with, because, based on prior history and
experience on similar projects, the criticality typically goes through this
work sequence.
The critical path can be represented by a single path or it could be represented by multiple parallel
paths. Figure 2-1 provides a simple example of a single critical path and multiple critical paths.
Analyzing the Critical Path
Ronald J. Rider, MBA
Table of Contents
1. INTRODUCTION ............................................................................................................................... 1
2. THE CRITICAL PATH DEFINED .................................................................................................. 2
3. IS THE CRITICAL PATH VALID? ................................................................................................. 5
4. STEPS TO CONSIDER FOR IDENTIFYING THE CRITICAL PATH ...................................... 9
5. CONCLUSIONS ............................................................................................................................... 16
List of Tables
Table 3-1 Schedule Quality and Deficiency Check Examples .................................................................. 7
List of Figures
Figure 2-1 Single and Multiple Critical Path Examples ............................................................................. 3
Figure 2-2 Critical Path Influenced by Constraint Example ....................................................................... 4
Figure 3-1 Sample Critical and Near-Critical Path Bar Chart Sort by Early Start Dates ............................ 6
Figure 4-1 P6 Menu Items to Create Critical and Near-Critical Path Codes ............................................ 10
Figure 4-2 Defined Critical and Near-Critical Path Code Menu............................................................... 11
Figure 4-3 Identify and Code Latest Finishing Activity Example ............................................................ 12
Figure 4-4 Identification of Driving Predecessors from Activity A9999 ................................................. 13
Figure 4-5 P6 Critical Path Grouping and Summarization Example ........................................................ 14
Figure 4-6 Final Critical Path Summary Example .................................................................................... 14
, Considerations for Identifying and
Analyzing the Critical Path
1. INTRODUCTION
The primary purpose of the time management function for a project is to plan, schedule, control,
and monitor the timely completion of the project’s scope of work. The standard method used
throughout the construction industry is to apply the Critical Path Method (CPM) scheduling
technique. The CPM scheduling technique is utilized by project management to plan, sequence,
forecast, and resource level the start and finish of work packages or schedule activities.
The all-important analysis tool provided by the CPM scheduling technique is the ability to
determine the critical activities that comprise the critical path. The critical path represents the
longest path or overall sequence of tasks and milestones that determine the project’s overall
duration. Activities not on the critical path will have some degree of float or slack time; activities
with available float or slack time can be delayed by the number float or slack days without
delaying the project’s overall finish date.
Project stakeholders must know, with a high degree of certainty, what the forecasted critical path is
in order to make sound and informed decisions relative planning the remaining work, applying
resources, dealing with potential delays, or accelerating portions of the project scope. CPM
scheduling programs allow users to select the activities that are considered to be on the critical
and/or near-critical paths by filtering the schedule data based on the longest path or low float value
criteria. The critical path and near-critical path output is typically in bar chart format or in tabular
report format.
Unfortunately, for large and complex engineering, procurement, and construction (EPC) projects,
the ability to quickly and accurately identify, summarize, and evaluate the critical path and near-
critical paths can prove difficult. It is not unusual for large EPC projects to contain multiple
process areas represented by tens of thousands of schedule activities, which makes identifying the
critical path and near-critical paths a burdensome endeavor. Further, the user is at the mercy of the
CPM scheduling program in terms of how the output of the schedule data is presented. In addition,
any deficiencies in the CPM model such as open-end activities and overuse of constraints further
complicate and muddle the process.
Therefore, it is up to the schedule analyst to use the confines within the CPM scheduling program
to better organize the schedule data in a format that the project participants can understand. The
purpose of this article is to discuss some of the challenges faced and steps to consider when
identifying and analyzing the critical and near-critical paths.
, Considerations for Identifying and
Analyzing the Critical Path
2. THE CRITICAL PATH DEFINED
The critical path is generically defined as the longest continuous path of activities, from the
progress date or data date to the final completion activity, which determines the overall duration
for a project. The activities that typically comprise the critical path are those activities with the
least amount of total float (i.e., zero or negative total float values). An activity on the critical path
is planned to not be started or completed until its logical predecessor activity or activities have
started or completed. If a critical path activity is delayed by one or many days, then any successor
activities including the project’s final completion activity will be delayed unless mitigations are
taken to recover the delay.
The following are two scenarios among many used to explain the rationale behind adopting a
certain critical path in a given situation:
a) Scenario No. 1 – A contractor may develop a critical path based on the
calculated result of the planned network logic and estimated activity durations
and other milestones included in the schedule; or
b) Scenario No. 2 – A contractor may develop a critical path based on the
collaborative input from the project manager, superintendent, subcontractors,
and/or others to force the critical path to go through certain activities that those
experienced people are satisfied with, because, based on prior history and
experience on similar projects, the criticality typically goes through this
work sequence.
The critical path can be represented by a single path or it could be represented by multiple parallel
paths. Figure 2-1 provides a simple example of a single critical path and multiple critical paths.
