Managing Schedule Slack/Float PMI Scheduling Forum January 6, 2015 January 6, 2015 Presented by: Ric Albani, PMP, PMI-SP, PMI-RMP, MCTS

Introduction U.S. Government Accountability Office (GAO) Published a Schedule Assessment Guide for Scheduling Best Practices. Developed as an accompaniment to a previously published Cost Estimating and Assessment Guide. Used across the federal government to develop, manage, and evaluate capital programs. Based on the concept that a well-planned schedule is a fundamental management tool for ensuring public funds are spent effectively. 2

Introduction GAO Schedule Assessment Guide 10 Best Practices: 1.Capturing all activities 2.Sequencing all activities 3.Assigning resources to all activities 4.Establishing the duration of all activities 5.Verifying that the schedule can be traced horizontally and vertically 3

Introduction GAO Schedule Assessment Guide 10 Best Practices: 6.Confirming that the critical path is valid 7.Ensuring reasonable total float 8.Conducting a schedule risk analysis 9.Updating the schedule using actual progress and logic 10.Maintaining a baseline schedule 4

Introduction Why care about float? Float is an indicator of a schedule’s flexibility. A delay to an activity does not always delay downstream activities unless float is evaluated. Activities with the lowest float values constitute the highest risk to schedule completion or interim milestones. An activity’s delay causes total float to decrease, thus increasing the risk of not completing the project on time. 5

Introduction On some projects: Effective management of both the critical path and float is lacking. Too much emphasis is placed solely on start and finish dates. Not everyone knows that two sets of scheduled dates exist for every activity: -Early Start/Late Start -Early Finish/Late Finish Not everyone knows that for most scheduling software: Start=Early Start and Finish=Early Finish 6

Calculating Total Float 7 Task A Task B Task D Task E Task C Task F StartFinish Forward Pass  calculates “early” dates  Backward Passcalculates “late” dates The difference between late and early dates is float

Calculating Total Float 8 Task A Task B Task D Task E Task C Task F StartFinish Path A-B-C is critical due to having zero slack Path D-E-F is non-critical with 1 day of slack

Float Definition Two Types of Float: Total Float is the amount of time an activity can be delayed or extended before the delay affects the project’s finish milestone. Free Float is the portion of an activity’s total float that is available before the activity’s delay affects its immediate successor. 9

Float Facts Can be positive, negative, or zero. Negative float usually results from having a constraint on an activity which is earlier than its calculated late finish. An activity with zero or negative total float is considered critical. Knowing the amount of time an activity can or cannot be delayed is essential to successful resource allocation and to completing the project on time. 10

Float Facts Float should not be treated as schedule contingency. Schedule contingency should be applied to specific activities according to prioritized risks. Activities on the same network path share total float. 11 Task X 5 days Task Y 3 days Task Z 1 day

Common Barriers to Valid Float Unreasonable amounts of total float usually result from missing or incomplete logic. Missing activities, missing or convoluted logic, and date constraints prevent the valid calculation of total float. Unrealistic activity durations; or un-statused work will distort the value of total float. Good schedule development techniques are imperative to having valid float 12

Reasonableness of Float Float will differ among activities given their logical sequence in the network and overall project duration. Large amounts of float may be justified given the activity’s place in the flow of work. Assess whether it makes sense logically that an activity with high float can slip that far without affecting the project’s finish date. If too little float is built into the schedule, then recovery from inevitable delay may be limited. Float should be evaluated equally along with start/finish dates 13

Float Management Management must: Know that the critical path can’t be correctly monitored without also monitoring float. Understand the amount of time an activity can or cannot be delayed to allocate resource and to re-sequence work. Balance the use of float knowing that float is shared along a path of activities. Know that free float is important in resource leveling since leveling usually targets activities with free float first. Determine what float value constitutes ‘critical’ by evaluating the project’s risk, urgency, technological maturity, complexity, and funding profile. 14

Total Float Checklist Ensure that:  Total float values calculated by the scheduling software are reasonable and accurately reflect true scheduling flexibility.  The project really has the amount of schedule flexibility indicated by the levels of float.  Any activities with high float are examined for missing or incomplete logic.  Total float values that are excessive are documented for justification.  Float for deliverables and milestones are evaluated for reasonableness. 15

Total Float Checklist Ensure that:  Total and free float are used to inform management as to which activities can be reassigned resources.  Management balances the use of float knowing that total float is shared along a path of activities.  Periodic reports are used to show the amount of float consumed in a period and remaining on critical and near- critical paths.  Date constraints causing negative float are justified. 16

Questions? 17

Ric Albani