Creating a project plan - notes

What is the Project Net Work?

Project network is a network of activities to complete the project.  It is a flowchart of activity that graphically depicts the sequence, inter dependencies and start and finish date of the projects   It also includes the leads, lags, duration of the projects etc.

•Provides the basis for scheduling labor and equipment.

•Enhances communication among project participants.

•Provides an estimate of the project’s duration.

•Provides a basis for budgeting cash flow.

•Identifies activities that are critical.

•Highlights activities that are “critical” and can not be delayed.

•Help managers get and stay on plan.

What is an Activity?

An activity is part of the project network.  It is an element of project that requires time. 

Merge Activity?

An activity which follows a series of activities.  A series of activities merging into one activity.

–an activity that has two or more preceding activities on which it depends.

Parallel / Concurrent Activities?

Two or more activities occurring at the same time.  

–Activities that can occur independently and, if desired,
not at the same time.

Path ?

A sequence of connected dependent activities.

Critical Path?

A longest path of a project network.  Has no slacks. 

–the longest path through the activity network that allows for the completion of all project-related activities; the shortest expected time in which the entire project can be completed. Delays on the critical path will delay completion of the entire project.

Burst Activity?

Multiple number of activities following one activity.  

–an activity that has more than one activity immediately following it (more than one dependency arrow flowing from it).

Basic Rules to follow in Developing Project Networks?

Each activity will have a unique number.  Numbers will increase as the diagram progresses. No loops.  

1.Networks typically flow from left to right.

2.An activity cannot begin until all preceding connected activities are complete.

3.Arrows indicate precedence and flow
and can cross over each other.

4.Each activity must have a unique identify number that is greater than any of its predecessor activities.

5.Looping is not allowed.

6.Conditional statements are not allowed.

7.Use common start and stop nodes.

ES, EF, ET, LS, SF, SL?

ES:  Early Start

EF:  Early Finish

ET:  Estimated Time Duration for that activity

LS:  Late Start

LF:  Late Finish

SL:  Slack

Forward Pass Computation?

–How soon can the activity start? (early start—ES)

–How soon can the activity finish? (early finish—EF)

–How soon can the project finish? (expected time—ET)

•Add activity times along each path in the network (ES + Duration = EF).

•Carry the early finish (EF) to the next activity where it becomes its early start (ES) unless…

•The next succeeding activity is a merge activity, in which case the largest EF of all preceding activities is selected.

Backward Pass Computation?

–How late can the activity start? (late start—LS)

–How late can the activity finish? (late finish—LF)

–Which activities represent the critical path?

–How long can activity be delayed? (slack or float—SL)

•Subtract activity times along each path in the network (LF - Duration = LS).

•Carry the late start (LS) to the next activity where it becomes its late finish (LF) unless

•The next succeeding activity is a burst activity, in which case the smallest LF of all preceding activities is selected.

Sensitivity?

–The likelihood the original critical path(s) will change once the project is initiated.

–The critical path is the network path(s) that has (have) the least slack in common.

Activities on critical path.

Have no slack

Laddering?

–Activities are broken into segments so the following activity can begin sooner and not delay the work.

Lags?
Use of Lags?

–The minimum amount of time a dependent activity must be delayed to begin or end.

•Lengthy activities are broken down to reduce the delay
in the start of successor activities.

•Lags can be used to constrain finish-to-start, start-to-start, finish-to-finish, start-to-finish, or combination relationships.

Hammock activity?

–An activity that spans over a segment of a project.

–Duration of hammock activities is determined
after the network plan is drawn.

–Hammock activities are used to aggregate
sections of the project to facilitate getting
the right amount of detail for specific sections
of a project.