August 02, 2019

Network Diagrams: Manual Vs Software Fundamentals

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Leveraging Manual and Software-Generated Network Diagrams:

The Microsoft Project Experience


Dr. Kene David Ewulu, EdD, MBA, MS, LEED-AP, PMP.

Adjunct Professor: Organizational Leadership, Business, & Project Management

Lead Coach: KDE Leadership, LLC.

June 2018


As a project management and leadership professor with the task of instructing undergraduate and graduate students on foundational and complex project management principles, I have observed that a good number of my students face a unique set of challenges with utilizing the Microsoft Project software in managing projects. This includes both novice and practicing project managers in my ground-based and virtual classrooms.

While compiling a work breakdown structure (WBS) and generating Gantt Charts for simple and complex projects is relatively simple, I observed that certain critical elements needed for optimizing planning and allocation of resources to tasks were difficult to produce. As the software produces a network diagram with a critical path outlined (often in depicted in RED), slacks for each of the project’s activities are not included within the activity boxes. This leads to guesswork from students and inexperienced practitioners on how to identify the most critical activities and optimally select non-critical activities for resource-levelling purposes.

This abstract aims to show how this discrepancy occurs, using two selected projects, and to guide readers on how to manually generate network diagrams that contain early-start (ES) and late-start (LS) values, activity slacks, and ultimately permutate total project float. With this, the project manager can accurately produce baseline plans and network diagrams to facilitate the future tweaking of schedules and resources during project execution.


The advent of project management software has revolutionized the management of projects in 21st century organizations. The ability to set up project scope, costs, schedule, and the project management plan before the commencement of project execution provides a baseline for monitoring and controlling them, and a guide to team members and other project stakeholders.

The Microsoft Project software is one very commonly used software; with its smooth interface with the Microsoft Office Suite of tools – MS Word, PowerPoint, and Excel. Of course, there are other powerful project management software out there, but this paper focuses on the comprehensiveness of MS Project regarding network diagrams and identifies some of its common challenges. Slacks and float help project managers determine how much room they have at their disposal to maneuver and tweak their projects when resources are scarce for critical activities, and which human resources to assign activities to based on their availability, leaves of absences, cost per hour, and family-work balance considerations. As such, accuracy at this step of the process is crucial to the success of any project.

In project management classrooms and during executive coaching sessions, this practitioner discovered that these same challenges abound, and that students were not able to comprehensively answer project-related questions that involve resource-levelling through either crashing or fast-tracking techniques. In the quest to effectively pass on the ability to identify slacks and floats, manually-generated network diagrams were embraced. The leveraging of forward and backward pass calculations enabled students and moderately experienced project managers to clearly identify activity slacks and see how to ‘borrow’ idle human resources for optimal periods of time to apply to potentially lagging critical path activities.

This paper will explain the dynamics of slacks, floats, and critical path activities by performing MS Project and manual network diagrams on two randomly selected projects from approved project management texts and comparing their outputs with each other.


Planning a project cannot be accurately done without first understanding certain concepts within the network diagram. The network diagram shows the graphical dependencies of activities, especially as certain activities must be concluded before others can begin, while some other activities do not have that relationship. The Work Breakdown Structure (WBS) is a “framework used for further planning, execution, and controlling of projects, and to progressively divide project deliverables into smaller pieces” (Kloppenborg, 2015, p.151). As a project manager formulates the WBS, he or she lists out the individual activities that must be performed to take the project from inception to completion, including the duration of each activity, as well as the activities that must be concluded before subsequent ones can start (predecessor activities).

Once this is completed within the MS Project platform, you can automatically generate the Gantt Chart by clicking on the Gantt Chart icon; this shows you a horizontal histogram or bar chart that indicates start and completion dates, as well as the resource personnel assigned to the activities. The Gantt Chart is described as “a bar chart of schedule information where activities are listed on the vertical axis, dates are shown on the horizontal axis, and activity durations are shown as horizontal bars placed according to start and end dates” (Kloppenborg, 2015, p.192). MS Project can also automatically generate the network diagram by clicking on the Network Diagram icon; this diagram shows the activity dependencies, and clearly identifies the critical path in RED. The critical path is defined in project management terms as the longest possible path from inception to completion, and/or the path where all activities have zero slack or the shortest possible time (Kerzner, 2013, p.600). By ‘zero slack’ we mean those activities that have no extra days added on; this means that it is crucial for them to be completed within the stipulated time, otherwise the project completion date will be delayed. Slack is defined as “the amount of time an activity can be delayed and not delay the project” (Larson & Gray, 2014, p.173).

To enable us to assess these phenomena and ascertain the proficiencies of both outputs, the author has selected the following project samples from popular college and graduate school project management texts.

Project Samples

Project 1 Description - Greendale Stadium Project (Larsson & Gray, 2014, p. 203)

This is a baseball stadium project that comprised of twenty activities with designated activity durations and dependencies. Students were required to formulate a work breakdown structure (WBS) based on the available data, generate a Gantt Chart and Network Diagram, and then utilize these tools to answer questions ranging from identification of critical paths, slacks, total float, and activities that could be tweaked to release idle resources for resource-starved critical activities. For the purposes of this paper, Microsoft Project-generated WBS, Gantt Chart, and Network Diagram, as well as a manually-generated Network Diagram were produced from the available data:

Network Diagram Variances and Inferences

 MS Project generated Work Breakdown Structures (WBS) have the capacity to give project stakeholders a visual presentation of the activities, dependencies, schedules, human resources, and the accompanying costs associated with the project. The histogram displayed forms the planning and supervision baseline for the project, giving project team members something to compare with progress and project status during execution. The accompanying MS Project software generated network diagram also identifies the critical path for the project.

However, manually calculating a network diagram allows us to leverage the activity slacks of activities NOT along the critical path to complete critical activities that for whatever reasons, are lagging behind and need an injection of more human resources to keep to established schedules of completion.

Project 1 - Greendale Stadium Project

Reviewing the manual network diagram for this project, you will notice there are five other paths that do not align with the two identified critical paths. The activities on these five paths are called non-critical activities, and you will notice they all possess some slack. For the purposes of this paper, we will select paths 2-3-8-20 (with a total float of 495 days), and 2-3-7-11-20 (with a total float of 365 days). From these two paths, we can borrow up to the maximum extra days available on each activity and apply those periods and the resource personnel attached to therein to any schedule-challenged activity along the critical path. Maximum periods of 210 days from activity #3 and 275 days from activity #8 can be borrowed from path 2-3-8-20, while maximum periods of 210 days from activity #3 and 155 days from activity #11 can be borrowed from path 2-3-7-11-20.

Project 2 – Product Upgrade Project

The manual network diagram for this project reveals two other paths that do not align with the critical path. These non-critical path activities are A-B-C-G with a total float of 20 days, and A-D-E-G with a total float of 20 days. Again, we can borrow from activities B (maximum of 10 days of slack), activity C (maximum of 10 days of slack), and/or activity E (maximum of 20 days of slack) and apply these periods and their attendant human resources to critical schedule-challenged activities along the critical path A-D-F-G.

Real World Applications and Conclusions

The capability of borrowing time and human resources from non-critical path activities and applying them to schedule-challenged critical path activities means that the manual network diagram is a “living thing”. It changes during project execution due to the project manager’s need to leverage idle resources. Critical paths can change from the baselines obtained during the planning stages of the project. This levelling of resources leads to a criticality of almost all paths along the network diagram, meaning that non-critical activities suddenly have less available, idle resources (less slack). The project manager therefore uses up more time, utilizes marginally more money (because the erstwhile idle resource personnel may be paid for the extra work they are now mandated to do), and most importantly, keeps to the original completion date planned into the project from the onset.

Does this now mean that MS Project should not be used for these projects? Far from it, because there are so many other reporting and tracking features that automation through MS Project affords the project manager. Furthermore, uploading the continually changing Gantt chart and network diagrams to a central virtual site allows other stakeholders access to progress reports, and helps keep team members on the same page.

It is recommended that project management practitioners be taught the skills required for utilizing MS Project, as well for manually generating network diagrams to ensure optimized performance in the field and in the classrooms.


Kerzner, H. (2013). Project management: A systems approach to planning, scheduling, and controlling (11th ed.). John Wiley & Sons, Hoboken, NJ.

Kloppenborg, T. (2015). Contemporary project management (3rd ed.). Centage Learning, Stamford, CT.

Larson, E. & Gray, C. (2014). Project management: The managerial process (6th ed.). McGraw-Hill, New York, NY.


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