Project Control Part 2

Scheduling Overview

To effectively plan and control a project, the project manager need to be able to process large amount of data quickly and accurately to ascertain the complexity of the resulting schedule. The activity network and the activity scheduled bar chart/GANTT chart are two of the key scheduling steps, which are central to successful time management planning, cost management and resource management planning. From the activity network, a structure is created to allow for project control and tracking including monitoring project progress, earned value management, information processing and project reporting.

The activity network and the GANTT chart provide a highly structured and methodical approach to project scheduling. Along with the project resource loading chart and cost requirements, they are fundamental to establishing the project baseline plan.

The scheduling steps continue from the project planning definitions given by the work breakdown structure (WBS) and the duration/cost estimations of work packages.

The major steps are:

    1 .     Define the relationships between activities

    2 .     Draw the activity network diagram

    3 .     Perform the network analysis

    4 .     Transcribe network analysis results to a GANTT Chart

    5 .     Introduce project “must dates”

    6 .     Optimize the activity network and resulting GANTT chart

    7 .     Build the cumulative cost estimate curve

    8 .     Establish and adapt the project’s resource requirements

With the advent of the project management software, there is a strong temptation to build the strong temptation to build the activity relationships and the network directly on the computer. The project manager must persuade the team members to avoid this, as not only is it extremely difficult to perform the precedence analysis on a computer screen, where few activities can actually be seen and the whole network be visualized, it most of all defeats all team dynamics objectives, as there is little or no active team member collaboration, participation, and eventual ownership. Use “brain ware” and “team ware” first, then use software.

Activity Networks

The first step before drawing the activity network is to determine the logical and physical dependencies of the work packages. Only activities are considered and ordered following a precedence analysis. The project manager and the team members will thus convert the hierarchal WBS to a sequenced network of activities. A network is not cyclical---there no loops, as every task must be connected to another task or event, thus creating paths over time.

The network is created based on assumptions about resource availability and estimated durations of each task, as well as on the evaluation of the interdependencies of work packages.

Determining the sequence of work packages

The convention in building a network of activities is to have a start activity at the beginning and finish at the end. Another convention is to show the flow of the network from the left to right and not top to bottom. Dependencies among work packages are defined and recorded for each. When the predecessors are identified for each work package, they should only be for immediate predecessors for a given work packages are possible and often exist.

Other than the start and finish, all work packages will have a predecessor and successor work package. The network must also include all dependencies and relationships to work package or events from and to external interrelated and concomitant projects.

The project manager must recognize:

     1.  Mandatory (physical) dependenciesà those dependencies that are inherent to the type of work being done. They cannot and will not change, no matter how many individuals are working on a task or how many hours are allocated to task.

     2.  Discretionary (logical) dependenciesà those dependencies that are defined by the project team, that offer the choice to the project manager to schedule tasks in a certain way.

     3. External dependenciesà outside the realm of the project or outside the control of the project manager, these dependencies may direct how portions of the project schedule must be defined.

Building the precedence chart of activities

Team work, the project manager and the core team will construct and visualize the activity network on a wall, using post is notes either taken from previous WBS structure or specifically developed for this step.

The activity network can then be illustrated either as an activity on arrow (AOA) or an activity on node (AON).

The activity on node network

The activity on node (AON), also called the precedence diagramming method (PDM), represents activities as the nodes, usually in the shape of a rectangle and the dependencies as arrows.

This type of activity network offers a variety of relationships that are discussed in the next section

Types of activity relationships

It is essential to establish the most effective physical and logical relationships for activities within the project’s network, as well as to correctly define the interfaces from and to other projects. Only with a solid structure and framework can the activity network subsequently reflect the calendar for the project and its required resources.

The AON/PDM is very powerful, in that it offers four types of relationships that allow for more flexibility in defining the precedence between activities. Furthermore, the AON/PDM allows for meaningful ways to accelerate or delay the schedule, as will be seen in section Lags and Leads.

There are four relationships, sometimes called constraints, which are explained further in the following sections:

       1.     Finish to Start – FS

       2.     Start to Start – SS

       3.     Finish to Finish – FF

       4.     Start to Finish - SF

There is an additional relationships, a hammock, which also explained below:

Finish to start relationships

The finish to start (FS) is the most common relationship. An activity can only start if the preceding activity has been totally completed. This relationship can be further developed by applying a delay between the two activities by use of a lag.

Start to start relationships

The start to start (SS) represents the relationship between the start dates of two activities. Precedence still exists between the two activities and the direction of the relationship is important, as the start of the successor activity is conditional only upon the start of the predecessor activity. During project implementation, any delay on the start of the predecessor will impact the start of the successor.

Finish to finish relationships

The finish to finish (FF) represents the relationship between the end dates of two activities. Precedence still exists between the two activities, and the direction of the relationship is important, as the end of the predecessor activity. During project implementation, any delay on the end of the predecessor will impact the end of the successor.

Hammock relationships

This is not a relationship per se. An extra activity, called a hammock activity, is introduced in the network to group a number of activities under one summary activity. It is often used to insert a higher level key highlight for faster and easier reporting to senior management, who only wish to capture the project’s important issues in the schedule at summary level.

Lag and Leads

Lags and Leads are techniques to introduce duration delays or accelerations in the network. These are used for all types of relationships.