220R89008 EPA SYSTEMS DEVELOPMENT CENTER Seminar Series: Designing and Implementing an Information System Seminar No.2: ' Project Scheduling- A Project Managers Perspective9 December 14, 1989 EPA Education Center Auditorium ------- PROJECT SCHEDULING: A PROJECT MANAGER'S PERSPECTIVE presented by Mr. Connie Teetz Planning Research Corporation December 14, 1989 ------- Seminar Objectives See where scheduling fits in the planning process Understand basic scheduling methods Be familiar with scheduling terminology Know what to look for in a schedule Recognize the value of automated scheduling tools ------- Schedule GRAPHIC WORK PLAN A sequential plan to accomplish work. It focuses on the tasks to be done and the timing of each task. ------- Setting the Foundation - Planning Determine the project objectives Break down the work into meaningful tasks Build a schedule Determine resource requirements Assign responsibility for the work Set up budgets Analyze risk Complete project plans ------- The Project Plan - A Systematic Approach An understanding of the objectives Elimination or reduction in uncertainties Improvement in efficiency A basis to monitor performance A baseline to manage change ------- The Project Manager's Role in Project Planning Effective organization Comprehensive planning Realistic schedules Solid estimates/budgets Measurement of progress Allowance for timely recovery ------- A Kev Step - Breaking Down the Work List the major tasks and deliverables Do a product oriented outline of the project Go to a level where work will be managed Set up a coding scheme Prepare short descriptions of work content ------- Medical Waste Information Project INFORMATION MANAGEMENT SYSTEM CONCEPT SYSTEM DESIGN / DEFINITION SYSTEM DEVELOPMENT / IMPLEMENTATION SYSTEM TESTING TRANSPORTATION NOTIFICATION DATA BASE MANAGEMENT TASKS ------- The Functions of a Schedule Logical sequence of the work Includes all "events", both internal and external Facilitates resource planning Supports the budgeting process Highlights critical tasks Provides a "road map" for the project The schedule validates the project plan ------- Network Schedules - A Brief History Program Evaluation and Review Technique (PERT) Arrow Diagramming Method (ADM) A statistical method using 3 or more estimates for data input. Term is used incorrectly to refer to current network methods t Task Precedence Diagramming Method (PDM) Task Task ------- Types of Schedules in Use Today Bar Chart (Gantt) Milestone Chart H-li 1 h I L Network Diagrams ------- Network Schedules - Loaic Diaarams Precedence Diagramming Method.... PDM - Activity-On-Node Arrow Diagramming Method.............. ADM Event-On-Node _ A B -o ------- Network Schedules - Terms Task (Activity) Event - Milestone Imposed date Constraint Calendar Critical path Float Early start/finish Late start/finish ------- Network Schedules - Constraints Constraints define the way tasks relate to one another - (dependencies) List the tasks and events of a network, then link them by drawing constraints Predecessor "Go Before" Successor "X*WWWĞĞ*ĞW*>W<0ĞĞ*W^-!*W'WW "Gome After" Constraint ------- Constraint Types Finish-to-Start FS - Successor cannot start until predecessor finishes Start-to-Start SS - Successor can start as soon as predecessor starts Finish-to-Finish FF Successor cannot finish until predecessor finishes Start-to-Finish SF - Successor cannot finish until predecessor starts G B 7Tj ------- Network Schedules Calculating Dates Forward pass Start from imposed start date and work forward through the schedule adding the duration of each activity along each path Backward pass Start with imposed end date and work backward through the schedule subtracting the duration of each activity along each path Imposed start ' EARLY START "Forward Pass" (Add Durations) EARLY FINISH TASK LATE START "Backward Pass" (Subtract Durations) LATE FINISH X . / Imposed finish ------- Network Analysis Attention focused on the identification of: Critical Tasks ("Schedule Float / Slack ) - Critical Tasks lie along the critical path ... a delay in any one of these tasks will impact the completion date of the project - Critical Path ... timewise, the longest sequence of connected tasks through a network. Usually, the path with zero or negative float ------- Network Analysis Concept Paper 10| System Design B 120 Data Collection a System Development Interim Review D 3 System Installation System Testing Data Entry H 60 Report Generation J I2°l = Tasks [Critical Path | ------- Network Schedules - Resource Scheduling Consider skills and/or specifications and mix/availability Initial estimates show usage profile and total usage A resource driven schedule may have different dates Usage profiles may cause overloads/underloads ------- What Do You Need To Get Started? A list of milestones A list of tasks The period of performance Specific delivery/need dates A work calendar ------- What Affects the Schedule? Durations Need dates Resource availability/limits Logic External events ------- Information Needed to Build a Schedule Calendars Project Wortt Task Data Task Number Task Name Description Duration Resource Information People Material Availability Other Constraint Data Imposed Dates, Lag, Lead, etc. Task Constraint Types (Relationships) FS Finish-to-Start SS Start-to-Start SF Start-to-Finish FF Finish-to-Finish PRECEDENCE (PDM) NETWORK ------- How to Track Progress Baseline Schedule Initial contractual work plan that is maintained for progress evaluations and trend analyses. Focus *~ Planned Performance Current Status J Current status causes changes in planned start/end dates. This may cause work-around plans and new projected completion dates Focus *- Deviations from Baseline f Operating Schedule '] Work plans that reflect work-around plans and new projected dates Focus Ğğ- Current Performance ------- Baseline Schedule The approved plan for the accomplishment of project objectives. . Necessary in order to measure progress/ performance Project manager should control any changes to the baseline schedule * The baseline schedule does not change when tasks slip ------- Operating Schedule The current, updated project schedule used to manage ongoing tasks Used to project revised start & finish dates for all remaining tasks Useful management tool estimating the cost to complete the project ------- As a Project Manager - What Questions Should You Ask? Are all tasks, milestones included? Are external events that effect the project included? Is the logic sound? Are the durations realistic? Are resource estimates accurate? Is resource utilization efficient? Is there any float (slack)? Is the level of detail appropriate? Can you understand the schedule? ------- Automated Schedulina Tools They help in the process - You still make the decisions! They can help outline the work (break it down into tasks) Most use a Bar Chart (Gantt) format for input They require duration and logic They can be very helpful in resource leveling They work best when you keep the number of activities low Great for "what if" exercises Know your requirements before you pick one ------- Summarv Scheduling is a key element in the planning process As a project manager, you play a very important role Know what to look for in a good schedule Use the schedule as a management tool Automated tools don't replace decisions ------- SCHEDULING TERMINOLOGY Activity - See Task Arrow Diagramming Method (ADMj A networking technique in which a task is shown as an arrow between two nodes representing events. Constraints are depicted as node-to-node relationships. Also known as Activity-on-Arrow or I-J (Interface-Juncture) method. As Late As Possible (ALAP) A scheduling technique in which the task schedule is computed by starting with its due date and working backward to determine the required start date. An ALAP task is scheduled immediately before its first successor. Also known as backwards scheduling. As Soon As Possible A scheduling technique in which the task is scheduled forward in time from the project start date to determine the required finish date. An ASAP task is scheduled immediately after its last predecessor. Also known as forwards scheduling. Backward Pass The procedure to establish when tasks and events must happen by calculating late start and finish dates with respect to project requirement dates such as the completion date. Barchart A format for displaying schedule data in which a task's planned time span is depicted as an open horizontal bar the ends of which correspond to the scheduled start and finish dates. The task's progress toward completion is shown by blackening the open bar along the time scale. Also known as a Gantt chart, named for Henry Gantt who first used the scheduling method in the early 1900's. Baseline A set of original or approved schedule dates that can be compared to actual start and finish dates to determine project status in relation to plan. ------- Calendar The definition of work periods (hours, days, weeks, months, years) and non-work periods (weekends, holidays, vacation time for labor resources) Coding Application of unique identifiers to permit sorting and selection of data and maintain traceability of a task within the network data base or between multiple linked data bases. Constraint A quantifiable relationship that ties network tasks and events together. Constraints both establish (task A cannot start until task B finishes) and qualify (task A can finish 2 weeks after receiving the output of task B) relationships among tasks. Also known as Dependency and Link. The following four constraint types are used to designate these relationships: o Finish-to-start (FS) - Task A (predecessor) must finish before Task B (successor) can start. This is the most commonly used constraint type. o Start-to-Finish (SF) - Task A (predecessor) cannot finish before Task B (successor) is started. This is the least commonly used constraint type. o Finish-to-Finish (FF) - Task B (successor) cannot finish before Task A (predecessor) is finished. A time value is sometimes applied to reflect the amount of work that Task B needs to accomplish after it receives the output of Task A. o Start-to-Start (SS) - Task B (successor) cannot start before Task A (predecessor) is started. A time value is sometimes applied to reflect the amount of work Task A must accomplish before Task B can start. ------- Critical Any task with zero or negative float. Critical tasks are those in which any delay in the task will delay the completion of the project. Critical Path The longest (with respect to the total time available) path of sequential tasks with the least amount of float in the network. The critical path is that string of tasks and events where a delay in accomplishing any one of them will jeopardize on-time completion of the project. Critical Path Method An analytical technique used to identify real or potential time reserve, predict the impact of critical task performance problems and evaluate the schedule impact of proposed solutions. Delay A time delay in a constraint indicating that tasks are constrained in the middle rather than the start or finish of their span time. Delay in a start-to-start constraint is a portion of the duration of the predecessor task, while delay in a finish-to-finish constraint represents part of the successor's duration. Delay may also be used to limit the number of scheduled tasks as in the case where shipping is considered a two-week lag in the constraint between production and installation tasks. See also Lag and Lead. Dependency - See Constraint. Dummy A task that can be used to build the network logic, but which does not represent any real work and cannot have resources applied against it; a really stupid person. Duration The amount of time required to start, perform and complete a task. Applying numerical values for duration to a task logic flow transforms it to a task network. ------- Duration-Driven Scheduling Scheduling only according to the time period required for work accomplishment without regard for resource requirements. Earlv Finish The earliest date on which a task can be completed as determined by network time analysis. Earlv Start The earliest date on which a task can be started as determined by network time analysis. Effort-Driven Scheduling - See Resource-Driven Scheduling. End A task with no logical successors; the last task in the network. Event An instant of time indicating the start or finish of a task or a project milestone; see also Imposed Date. Float The time value difference between when tasks can happen (early start/early finish) and when the must happen (late start/late finish). Also known as SJ.ack or time reserve. Float is that amount of time that tasks can slip without delaying other tasks in the schedule. See also Free Float and Total Float. Forward Pass The forward computation procedure for establishing the earliest expected start and finish dates for tasks (early start/early finish) based on their durations and constraints. ------- Free Float The amount of time a task may be delayed without affecting any of its successor tasks. Gantt Chart - See Bar Chart. Hammock A technique for summarizing detailed tasks or subnetworks where start and finish events represent the earliest start and latest finish of a set of tasks. Histogram A vertical barchart where resource utilization rates are displayed vertically across a horizontal time scale. Imposed Date A "due by" or "need by" date established independently of the network development process. Project milestones are generally established as imposed dates. Lag The amount of time after a predecessor task finishes that a successor task can start in a finish-to-start relationship. See also Delay. Late Finish The latest date a task can complete without affecting any successor tasks or the project completion date. Late Start The latest date a task can start without affecting any successor tasks or the project start date. Lead The amount of time before a predecessor task finishes that a successor task can start in a finish-to-start relationship. See also Delay. Link - See Constraint. ------- Logic Diagram Graphic depiction of the relationships among tasks that shows the sequence and flow of project work; generally a logical layout of the project WBS Loop A network logic error in which tasks are so constrained that it is impossible to perform a time analysis because each task is its own predecessor and/or successor. Master Schedule A schedule depicting the entire project plan, generally at a summary level. The master schedule may be displayed in either barchart or network diagram formats. Milestone A key occurrence in the project schedule such as project start, design reviews, delivery date and project finish. Generally scheduled as a zero duration event. See also Event and Imposed Date. Negative Float The result of a condition where a task's early dates are later than its late dates; insufficient time to complete the task; also known as negative slack. Network Diagram A flow chart of the project plan showing task durations, constraints and the critical path. PERT Analysis A method of computing expected task duration where the weighted average of optimistic, most likely and pessimistic duration estimates is determined. PERT is the acronym for Program Evaluation and Review Technique developed for the Polaris submarine program in the 1950's. Percent Complete A measure of work accomplishment that compares the amount of effort completed with the total task effort to be completed; also known as physical percent complete. ------- Positive Float The result of a condition where a task's early dates are earlier than its late dates; more than adequate time to complete the task; also known as positive slack. Precedence Diagramming Method fPDM) A networking technique where tasks are represented by nodes (rectangular boxes) and constraints are shown as lines between the nodes. Also known as Activity on Node. Predecessor A task or event that logically flows into another activity or event. Project A set of tasks that must be performed to reach a specified objective. Resource People and material required to accomplish a task. Resource Allocation The process of assigning resources to a task. Resource Conflict A condition in which a resource workload exceeds its availability; also known as resource overload. Resource-Driven Scheduling A scheduling method that determines task durations based on the amount of resources available for task accomplishment. Resource Leveling Delaying tasks in the scheduling process until the required resource is available; scheduling so as not to exceed the availability of required resources. ------- Resource Pool A set of resources that may be shared among several projects. Selection Derivation of only specified schedule data that meets defined criteria. For example, selection of only those tasks with an early finish date before a required delivery date. Slack - See Float. Sort To order in a specified manner. For example, a sort by early start would list the earliest task first followed by the next chronological task. Any task without a constraint into its start. Successor A task or event that logically follows another task or event. Target Date - See imposed Date Task Performance of effort in terms of resources required over a specified period of time; generally the smallest unit of work that can be scheduled; also known as an Activity. Time Analysis The process of running a forward and backward pass through the network to determine early start/early finish and late start/late finish dates for each task. ------- Total Float The amount of time a task can be delayed without affecting the completion date of the project. Zero Float The result of a condition where a task's early dates are equal to its late dates; just enough time to complete the task; also known as zero slack. ------- |