Scheduling

Putting the activities in chronological order –Chicken or the egg Allows the PM to determine the time required to complete a project

Types of Schedules Depend on Viewer –Simple bar chart (Gantt chart) Tells owner progress –Activity on Node (AON) –Activity on Arrow (AOA) Used by PM, supers, foremen –Short term schedules Monthly, allows for close-up look at schedule

Developing Activity Sequence Physical Relationship An activity cannot start until a previous one is complete Safety Relationship Performing activities which cause a safety hazard to other activities Resource Relationship The amount of resources available at any time Preferential Relationship Contractors preference on activity order

Constructing Bar Chart How should bar chart be laid out –Time on horizontal axis –Activity on vertical axis –Time of activity start based on position –Duration of activity based on length of line Day = start of day to start of day

Constructing Bar Chart What time unit should be used –Work days –Hours –Weeks –What makes sense for your project –Bar chart size may dictate time units –Time unit dictates activity size

Constructing Bar Chart Additional Info –Activity Value –Activity Cost –Activity Resource requirements

Constructing Bar Chart Work days or Calendar days –Work days harder to follow No weekends or holidays –Calendar days allow you to see concrete curing

Gantt Chart Looks like a horizontal bar chart Good for linear work Good for providing an overview of the project Not good for complex projects

Gantt Chart

Owner’s Chart

Activity Network Development Network Models Activity on Node Precedence Diagram Method Activity on Arrow Network Characteristics Discrete Activities Deterministic Durations Deterministic Logic Activity Flow

Network Elements Activities Basic building block Represent tasks Must consume time and resources Milestones Notice to Proceed Building Enclosed Substantial Completion Project Complete Activity Relationships Physical, Safety, Resource, Preferential

Precedence Succeeding activities cannot start until preceding activities finished Changes in duration of one activity affect all succeeding activities

Activity on Node All activities occur at nodes Arrows connect nodes and show relationships

Activity on Node Basics: Unique Alphanumeric identifier Unique description Estimated Duration Succeeding activity cannot start until preceding activity is finished Need beginning and ending milestone to tie project together

Constructing an AON Network Sequential logic –All activities preceding must be finished before next activity can start Concurrent Logic –2 or more activities can be worked at one time

Constructing an AON Network Multiple Successor Logic –2 or more activities can be worked at one time after common predecessor is finished Multiple Predecessor Logic –2 or more activities need to be finished before next activity starts

Constructing an AON Network Combinational Logic –2 or more activities can be worked at one time after multiple predecessor activities are finished

Logic Errors and Problems Incorrect Logic Activities MUST have a logical connection Paint color does not control the roofing application Redundant Logic –Not incorrect –Can cause errors

Logic Errors and Problems –Logic Loops

Activity Numbering Numbering Activities can make it easier to use schedule Group like activities under the same general numbers –Activity Category WBS can make it easy to categorize resources used to each activity –Work Classification Numbers refer to a class of activity

Activity Numbering –Location Number activity based on location on project –Responsibility Numbers refer to who is responsible for work

Activity Numbering Numbering Conventions –Directional Numbers increase from start to finish of project –Numbering gaps Leave gaps between numbers to allow for additions to schedule –Even/Odd Numbering Even # = part of base contract Odd # = additional work

Constructing a AON Determine the relationships between the activities Forward Pass –Determine when each activity can start based on the finish of the predecessor activities Backward Pass –Determine when each activity can start based on when the successor activities start

Constructing a AON ActivityDurationPredecessors A6 B4A C10B D C E1D,G,I F6A G8F H10A I6H

Constructing a AON Critical Path –Path through schedule which provides the shortest time to complete project Total Float –Amount of time that activity can float without impacting CP Free Float –Amount of time an activity can be delayed without effecting the early start date of the successor activity

Reviewing the Schedule Is Schedule complete Are Activity Duration Reasonable Are Activity Relationships Complete Are Activity Relationships Valid Is Project Calendar Correct Is Schedule Duration within Contract Time Are Contractual Milestones Met

Analyzing the Schedule Is Critical Path Reasonable Are there Multiple Critical paths What Activities are Near Critical How does Work Flow Are there Conflicts Among Concurrent Activities Is there an Excessive amount of Work at any Time

Value Engineering Provides alternatives to the proposed design –Save Owner $$ –Must be as good or better than original design –Must save enough $$ so that contractor can recover his cost of doing VE –Usually comes from contractor’s or engineer’s previous experience

Value Engineering Can save $$ either due to savings in time or materials –Ex: Composite Wall and roofs –Material cost per sf is higher than regular roof –Labor cost is lower –Requires a crane

Value Engineering Ex: –Replace infiltrators with Eljen In drains System size is reduced to 50% Also reduces amount of sand, clay, topsoil Reduces dozer time and installation time In-drain costs about 2x infiltrator

Updating Schedule Frequency –Depends on Complexity –More complex -> more updates Unexpected events –Update after event to determine new completion date –Helps team evaluate strategies to mitigate impacts When specified –By contract documents

Updating Schedule How –Gather Activity Status Info Update Date – when the info is gathered Activity status –Actual start date – meaningful work begins –% complete »Work in place -> work in place/planned work quantity »Time expended -> time expended/ planned duration (only good for time dependent activities like concrete curing) »Cost Incurred - >cost incurred/planned cost (depends on actual resource productivity being constant and resource costs not varying) »Resource used -> Resource Used/Planned resource amount

Updating Schedule How –Activity status –Remaining duration – Remaining Work quantity/Anticipated Productivity –Actual finish date – all completed activities »Provides data for future jobs –Gathering Data Direct observation, Update meetings, field reports, turnaround reports, photos and videotape

Analyzing Schedule Status What is the basis for evaluating schedule status? –Usually the original schedule is the baseline What is planned completion date –Is updated schedule completion date same as baseline If not – why not (is there an error)

Analyzing Schedule Status Has the critical path shifted? –If so – why –Are CP activities really “critical” Has the float changed on any activities? Has weather become a factor for any activity Are there trends worth watching Any changes since last update?

Modify and Revise Schedule Revise network logic –Change duration to meet contracted completion –Reflect changes in planned means and methods for completing activity –Shift activity to better time (summer for concrete)

Modify and Revise Schedule Revise Activity Durations –Planned quantity of work has changed –Amount of resources has changed –Productivity is either higher or lower than planned Add & Delete Activities –Scope of work changed –Activities divided into smaller activities

Review and Analyze Schedule Make sure new schedule does not contain errors Implement updated schedule

Out of Sequence Work Why? –Keep crews busy –Preparatory work starts early Gives crew a chance to test means and methods Preserve Schedule Logic –Shorten successor activity caused by out of sequence work –Keep all other logic intact