Project Scheduling Overview
Project scheduling establishes the sequence and duration of activities from design through construction closeout. The ARE tests your ability to read schedule diagrams, understand scheduling techniques, and know when to apply schedule compression strategies.
Gantt Charts
A Gantt chart is a horizontal bar chart showing tasks against a timeline. Each bar represents an activity's duration, with start and end dates plotted on a calendar axis. Gantt charts are easy to read and communicate schedules to owners, but they do not clearly show task dependencies the way network diagrams do.
Critical Path Method (CPM)
CPM is a network-based scheduling technique that identifies the sequence of dependent activities determining the shortest possible project duration - the critical path.
Key Terms
- Critical path: The longest chain of dependent tasks; any delay here delays the entire project.
- Float (slack): The amount of time an activity can be delayed without affecting the project finish date. Critical path activities have zero float.
- Free float: The time an activity can slip without delaying the start of the next activity.
- Predecessor/successor relationships: Finish-to-start (most common), start-to-start, finish-to-finish, and start-to-finish logic ties.
Forward and Backward Pass
CPM calculations use a forward pass to determine early start/early finish dates and a backward pass to determine late start/late finish dates. The difference between early and late dates at each activity equals its float.
Schedule Compression
| Technique | Description | Trade-off |
|---|---|---|
| Fast-tracking | Overlapping activities normally done sequentially (e.g., starting construction before CDs are complete) | Increased risk of rework and coordination errors |
| Crashing | Adding resources (labor, equipment, shifts) to shorten critical path activities | Increased cost, often nonlinear |
Fast-tracking is common in design-build and CM at-risk delivery, where overlapping design and construction phases is a primary driver for selecting that method.
Milestones
Milestones are zero-duration markers representing key events (permit issuance, substantial completion, occupancy) used to track progress against contractual dates without representing actual work.
Precedence Diagramming Method (PDM)
PDM represents activities as nodes (boxes) connected by arrows showing dependency logic, the most common format for CPM schedules in construction software (e.g., Primavera, MS Project).
Applying Schedules on the Exam
- Be able to identify the critical path on a simple network diagram by finding the path with zero float.
- Understand that delaying a non-critical activity within its float does not delay the project.
- Recognize that adding resources to a non-critical path activity does not shorten overall duration.
Exam Tips
- Practice forward/backward pass calculations - these appear as calculation-based items.
- Know that float belongs to the project, not any one party, which matters in delay-claim disputes covered under Construction Administration.
- Connect scheduling decisions to budget impacts in Cost Estimation.
Scheduling questions are a staple of PcM and PjM - build your fluency with AREprep's practice exams.