Steps to Building a Baseline Schdedule

A baseline schedule is more than just a list of tasks to be completed; it is the official project roadmap. It establishes how the work will be executed, measured, and reported. A strong baseline is essential for accountability, accurate forecasting, and effective risk management. Prior to developing a baseline schedule, you need to determine the CPM Scheduling Tool you plan to use. The two most common softwares are Microsoft Project and Primavera. 

Let’s review the steps of developing a high-quality baseline schedule using CPM principles, with practical tips for MS project users. 

Step 1: Define Scope and Deliverables (WBS)

• Break the project down using a Work Breakdown Structure. 
• Start at the top with project phases, then work down into smaller, more manageable components.

WBS Hierarchy Summary:

Example: 

• • WBS (Phase): Pre-Construction
    • WBS (Work Packages): Site Analysis
      • (Activity/Task) Geotechnical Survey
      • (Activity/Task) Environmental Assessment
      • (Activity/Task) Site Survey

Step 2: Develop Activities

• Turn deliverables into activities: Each activity should represent a single piece of work, assigned to a single party ,with a start and a finish.
• Activities should use action based language (pour concrete slab, install framing) 
• Activity names should be unique and never duplicated. Use location information in the activity name to help achieve this.
• Avoid lumping weeks of work into one line. Break tasks up into manageable durations.

Step 3: Assign Durations

• Assign a duration to each task.
• Use realistic estimates that are based on productivity rates, crew sizes, and available resources.

If possible, validate your durations based on similar past projects.

Step 4: Establish Logic Ties

• Link activities using dependencies:
  • Roughly 80% or more of your relationship ties should be Finish-to-Start.
  • Apply Start-to-Start or Finish-to-Finish only when it reflects reality. 
  • Start-to-Finish should be rarely used, if ever. Prior to using Start-to-Finish, attempt to replicate the relationship with a different logic tie. 
• Every activity should have at least one predecessor AND one successor (except the start and finish milestones) 
• Avoid dangling/unbound activities by ensuring each activity has at least one FS or SS predecessor and one FS or FF successor
• Keep dependencies logical by representing actual physical or contractual relationships, not personal preference. 
• Ensure crew flow is reflected through the presence of crew logic. Usually, after each activity, two things happen: 1.) A new activity in the same area can start 2.) The crew who just finished the task goes somewhere else. Make sure that is evident.

Step 5: Apply Calendars and Constraints

• Set working calendars based on project specific workweeks, holidays, and weather considerations.
• Assign calendars to the project and at the task level as needed (ex: your electric crew is working a 6 day work week, where all other trades are using a 5 day workweek)
• Only use constraints such as must start on or must finish on if contractually required. 
  • Use sparingly
  • Process for adding a constraint

Step 6: Validate the Critical Path

• Highlight the critical path in MS project by clicking the “Critical Tasks’ box in the Gantt Format Tab at the top of the schedule/
• If the path seems unrealistic, revisit your logic and durations. 

The critical path should align with field execution. If it doesn't, your schedule forecast may not match reality. 

Step 7: Save and Communicate the Baseline

• Save your schedule as the project baseline.
• Document your assumptions by keeping a record of durations, logic decisions, and calendar setups

Ensure the project team and owner agree that the baseline reflects how the work will be executed.