November 20, 2023
Schedule Quality Checks to Consider
This blog post addresses schedule quality checks to improve the accurate identification of critical and near-critical paths on construction projects.
This is the fourth post in a five-part series that discusses critical path validity. The first post discusses the purpose of time management on construction projects, the second post concerns defining the critical path, and the third post addresses challenges to validating the critical path. The fifth post discusses steps to consider for identifying the critical path.
Deficiencies or errors in the schedule, if not corrected, could substantially affect the accuracy of forecasted critical and near-critical paths. Therefore, schedule quality checks should be considered a requirement when assessing the critical and near-critical paths. Table 1 lists some common quality and deficiency checks to consider.1
Schedule Quality and Deficiency Check Examples
|Item No.||Quality/Deficiency Check||Description|
|1||Missing Work Scope||Review contract documents and work scope estimates to verify to the extent possible that the schedule file represents all required contract scope. Commonly missed work scope activities include the submittal process, owner or contractor approvals, customs clearance, quality assurance and control, concrete cure periods, pre-commissioning steps, punchlist requirements, and the turnover process. Correcting the schedule file for missing work scope activities could change forecasted dates and potentially alter the critical and near-critical paths.|
|2||Excessive Number of Open-End Activities||Open-end activities are defined as having no predecessor activity, no successor activity, or both. Good scheduling practice requires a minimal number of open-end activities except for: (1) the project start activity (no predecessor activity); and (2) the project completion activity (no successor activity).|
A large number of open-end activities can create erroneous float values and cause forecasted activity sequences to be performed illogically (i.e., excessive float from the data date to project finish). Correcting open-end activities can change float values that may affect the forecasted dates for critical and near-critical activities.
|3||Large Number of High-Float Activities||A large number of high-float activities in a project schedule may indicate underlying schedule quality problems. Schedule paths with high float values typically result from open-end activities discussed in Item 2 above, artificially constrained activities, or lack of workflow optimization on the part of the contractor. Schedules with many high-float activities should be thoroughly examined and corrected for any open ends or missing logic links to better optimize forecasted dates and float values.|
|4||Inconsistent Use of Schedule Calculation Modes||Retained logic is the default calculation mode for nearly all scheduling software programs. Another scheduling calculation mode is progress override, which allows out-of-sequence work activities to progress without delay, regardless of whether or not logical predecessors are complete. Progress override is based on the premise that a contractor has all the labor, equipment, and supervision resources required to work in multiple areas concurrently.|
Many contractors use progress override to update a schedule without having to spend time correcting out-of-sequence work. In some cases, contractors switch schedule calculation modes during the project from retained logic to progress override and then back to retained logic without reason. Inconsistent use of schedule calculation modes can create problems. Switching to a consistent mode may change the critical and near-critical paths.
|5||Overuse of Constraints||The number of constraints applied to activities should be checked. Constraints are restrictions imposed on either the start or finish of an activity that may artificially lock down schedule activity dates and prevent them from naturally “flowing” during forward and backward pass calculations to determine activity float values and the critical path.|
While contractual requirements may necessitate some constraints, the overuse of constraints could cause discontinuities in the critical and near-critical paths between the data date and the final completion activity, thereby masking the true critical path. Fixing problems caused by overuse of constraints could alter the critical and near-critical paths.
|6||Misapplication of Calendars||If activities are assigned to the wrong workday calendar, such as a five-day work week rather than a seven-day work week, critical path calculations may be incorrect. Schedule calendar definitions should be reviewed, and then critical and near-critical activities should be evaluated to verify which calendar applies to each activity. Calendar assignments should be evaluated for reasonableness based on where each task is performed and which project resources are assigned.|
If a schedule model contains one or more of the problems identified above, this may materially impact, directly or indirectly, the reasonableness of the critical and near-critical paths. If not corrected, these issues may compromise important project decisions, including the application of limited resources. Correcting the mistakes listed above could involve an iterative process requiring time and effort by the project team.
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Challenges and Considerations in Identifying and Analyzing the Critical Path
This first post in a series on identifying and analyzing the critical path discusses the purpose of time management on construction projects.
The Critical Path Defined
This post explores various kinds of critical paths. It is the second post in a series on identifying and analyzing the critical path.
Is the Critical Path Valid?
This post addresses challenges to determining the validity of the critical path. It is the third post in a series about critical path validity.