Primavera P6 stands as one of the most powerful scheduling tools in construction management, yet even seasoned professionals can stumble when using it. A single scheduling error can ripple through your entire project, causing delays, budget overruns, and frustrated stakeholders. Let’s explore the most common P6 scheduling mistakes and learn practical strategies to avoid them.
Mistake #1: Incorrect Activity Sequencing
Activity sequencing forms the backbone of any construction schedule. Many managers create schedules in which activities appear in the right order on the Gantt chart but lack proper logical relationships. This creates what schedulers call “dangling activities”—tasks that float in time without clear connections to other work.
The most common sequencing errors include:
- Using only Finish-to-Start relationships when Start-to-Start or Finish-to-Finish would be more appropriate
- Creating “spider webs” of unnecessary relationships that complicate schedule logic
- Missing key dependencies that affect the critical path
Solution: Map out activity relationships on paper before entering them into P6. Use the appropriate relationship type for each connection. Remember that Start-to-Finish relationships are rarely used in construction. After entering relationships, use P6’s Schedule Log to check for missing logic ties.
Mistake #2: Improper Resource Loading
Resource loading mistakes can make your schedule look good on paper but fail in execution. Common errors include:
- Assigning resources without checking their availability
- Not accounting for varying skill levels among crew members
- Failing to consider equipment mobilization time
- Overallocating resources across multiple activities
Solution: Create accurate resource calendars before loading them into activities. Use P6’s Resource Usage Profile to identify overallocation. Consider using role-based resources instead of specific individuals for better flexibility. Always verify that resource availability aligns with your project calendar.
Mistake #3: Neglecting to Update Baselines
Your baseline schedule represents your original plan against which you measure progress. Many managers set an initial baseline and never update it, even after significant project changes. This makes variance analysis meaningless and performance tracking inaccurate.
Solution: Establish a baseline maintenance protocol. Update baselines only for approved change orders that affect the schedule. Keep historical baselines to track how the project plan evolved. Use P6’s baseline comparison features to identify schedule slippage early.
Mistake #4: Calendar Setting Errors
Calendar mistakes create some of the most difficult-to-diagnose schedule problems. These include:
- Using the default calendar without customization
- Not accounting for local holidays and weather-affected workdays
- Creating conflicts project and resource calendars
- Forgetting to apply calendars to activities
Solution: Create project-specific calendars before scheduling any work. Include all holidays, expected weather days, and other non-work periods. Ensure resource calendars align with project calendars. Use P6’s Global Change feature to update calendar assignments across multiple activities.
Mistake #5: Poor WBS Structure
A poorly structured Work Breakdown Structure (WBS) makes schedule management unnecessarily complex. Common issues include:
- Creating too many levels that add no value
- Inconsistent work package sizes across the project
- WBS that doesn’t match contract requirements
- Missing deliverable-based organization
Solution: Follow the 100% rule – every level should account for all work below it. Keep work packages between 8-80 hours of effort when possible. Align your WBS with contract milestones and reporting requirements. Use P6’s WBS templates for consistency across projects.
Mistake #6: Ignoring Schedule Quality Metrics
Many managers focus solely on completion dates while ignoring schedule health indicators. Key metrics often overlooked include:
- Activities without predecessors or successors
- Excessive use of constraints
- High total float values
- Long lag durations
Solution: Run P6’s Schedule Log regularly to identify quality issues. Keep constraints to a minimum – if you have more than 5% of activities constrained, review your logic. Document the reason for every constraint used. Aim for total float values that make sense for your project type.
Mistake #7: Inadequate Progress Updating
Infrequent or inaccurate progress updates render even the best-planned schedule useless. Common updating mistakes include:
- Updating schedules monthly instead of weekly
- Not collecting actual start and finish dates
- Using percentage complete without supporting data
- Failing to document delays and changes
Solution: Establish a weekly update cycle. Train field personnel to collect accurate progress data. For more accurate tracking, use physical percent complete instead of duration percent complete. Document all changes and delays in P6’s notebook feature.
Best Practices for Avoiding These Mistakes
To maintain schedule quality:
- Create a schedule development checklist
- Implement peer reviews before issuing schedules
- Maintain schedule specifications for consistency
- Conduct regular schedule health checks
- Keep detailed schedule logs and documentation
How The Swaney Corporation Can Help
Avoiding these P6 scheduling mistakes requires expertise and experience. If organizing your Primavera P6 Scheduling is overwhelming you, call The Swaney Corporation / Crowe Construction Inc., and we can create a specific solution for you. We offer:
- Expert P6 scheduling services to prevent these common errors
- Schedule audits to identify and correct existing issues
- Training programs for your project management team
- Claims prevention through proper schedule management
Don’t let scheduling mistakes derail your construction project. Contact The Swaney Corporation today at (707) 665-9668 to ensure your P6 schedules support project success rather than hinder it.