The Schedule Quality Index™

With the recent launch of the Fuse Schedule Index Calculator, we often get asked, what is the Schedule Quality Index™ and how is it calculated? 

First and foremost the Schedule Quality Index is a means of assessing how well planned a schedule.  It is a single score that is calculated from nine separate schedule check metrics.  The metrics span multiple key attributes, or building blocks of a schedule that together from the underpinnings of a structurally sound schedule. 

The Schedule Quality Index is made up of the following nine checks (metrics):

Missing Logic

In theory, all activities should have at least one predecessor and one successor associated with them. Failure to do so will impact the quality of results derived from a time analysis as well as a risk analysis. This number should not exceed more than 5%.

Logic Density™

This metric calculates the average number of logic links per activity. An average of less than two indicates that there is logic missing within the schedule. An average greater than four indicates overly complex logic, with a high likelihood of redundant links. Therefore, Logic Density™ should be between two and four.


While a highly critical schedule is not necessarily a sign of poor scheduling, it can indicate a highly risky schedule. Use this metric as a point of reference.

Hard Constraints

Hard, or two-way, constraints such as ‘Must Start On’ or ‘Must Finish On’ should be avoided. Use of such constraints can lead to inaccurate finish dates and a lack of insight into the impact of schedule changes, risk events, and earlier delays.

Negative Float

Negative float is a result of an artificially accelerated or constrained schedule, and is an indication that a schedule is not possible based on the current completion dates.

Insufficient Detail™

Activities with a high duration relative to the life of the project are an indication of poor schedule definition. Detail should be added to the schedule.

Number of Lags

A lag is a duration applied to a logic link often used to represent non-working time between activities such as concrete curing. Lags tend to hide detail within the schedule and cannot be statused like normal activities; therefore, lags should be converted to actual activities with durations.

Number of Leads

A lead, also known as a negative lag, is often used to adjust the successor start or end date relative to the logic link applied. This is a poor practice as it can result in the successor starting before the start of the predecessor.

Merge Hotspot

A merge hotspot is an indication of how complex the start of an activity is. If the number of links is greater than two, there is a high probability that the activity in question will be delayed due to the cumulative effect of all links having to complete on-time in order for the activity to start on time.

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Planning & Scheduling rules/principles


Planning & Scheduling rules/principles

Let us first understand the terms i.e., planning & scheduling:

Planning is control of time on a project by:

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New Approaches to Level Scheduling

One of the most important considerations of project planning is the scheduling of a project at the right level, at the right time - and that can be challenging. Executive-level and senior-level management scheduling have different needs and goals than stage- or phase-level scheduling, which may require more detailed planning.
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Scheduling and the ‘Progress Override v Retained Logic’ Conundrum

Scheduling and the ‘Progress Override v Retained Logic’ Conundrum

With the growing use of project management software to analyse construction delays, comes the often overlooked question – how does the software really work? This is of course a pretty meaty query and way too big for a single article. But within it are some more manageable ‘bite-sized’ issues. One of these is programme scheduling and how out-of-sequence working is rationalized by the software during the scheduling process. Now whilst some might consider the usefulness of this topic limited to the planners’ amongst you, it is important to recognise its wider implications upon defining and quantifying critical path delays.

So what is ‘programme scheduling’?
In a nutshell, scheduling is the process of updating a programme to a certain date during the course of a project (often referred to as the ‘data date’) by incorporating progress information for all activities in the programme up to that point in time. On many projects this is done at least once a month, with the updated programme included in the monthly progress report. The process itself involves adding actual start/finish dates, the percentage complete, and remaining duration of individual activities that have in some way changed over the reporting period. Once this information is added, the programme is scheduled (or rescheduled), calculating new start/finish dates for all activities in the programme according to a bunch of preset logic rules defined by the operator.
The average construction programme invariably contains many thousands of these user defined logic rules. These rules transform a static bar chart into a much more useful dynamic model which can be gradually updated with progress and other changes to assist managing the project and tracking delays. These rules include things like:- (a) logic relationships between activities (e.g. task A must be complete before task B can start); (b) different working-day calendars for specific types of tasks; and (c) resource dependent activity durations.
In addition, they also include a choice between using the Progress Override or Retained Logic options when dealing with out-of-sequence progress of activities (i.e. when an activity progresses in advance of when it otherwise would have according to the prevailing logic rules). When the Progress Override option is chosen, work is allowed to proceed on the out-of-sequence activity immediately and the logic links from its predecessor activities are overridden. If the Retained Logic option is chosen, these predecessor links are not overridden and remain in force thereby governing when the remainder of the out-of-sequence activity will be carried out.
Figure-1 and 2 are included below to help show the difference between these 2 operations.
Figure-1 shows 2 activities, A and B, where activity A was planned to be fully complete before the start of B. This is known as a finish-to-start logic link.
Figure-2 then demonstrates how the software deals with the situation where, during the works, activity B starts before A is complete. If the Retained Logic option is used, the remaining duration of activity B is scheduled to occur after A is complete. In contrast if the Progress Override option is chosen, then the finish-to-start logic between activity A and B is ignored or overridden. In this case activity B is allowed to progress notwithstanding that A is not finished.
The end result is that the Progress Override option leads to an earlier projected finish date for activity B. It also means that activity A is no longer on the critical path at the time of the progress update.
The wider implications of this choice will hopefully become clearer after working through an example. Consider a hypothetical reclamation project with a contract duration of 8 months. Upon commencement the Contractor is to carry out preliminary site investigation of the seabed and then prepare a detailed dredging layout plan. Once this is approved by the Engineer, the Contractor is to proceed with dredging, followed by construction of a rock filled seawall. The final stage is to place sand fill behind the seawall up to formation level. The corresponding programme is set out in Figure-3 below.
Now consider the situation as at the end of Month-2. Say that site investigation and drawing preparation proceeded as-planned. However, whilst generally accepting the submitted dredging layout, the Engineer would not formally approve the drawing until he had ‘checked a few things’. In response the Contractor decided to proceed with dredging and make any minor amendments (if necessary) after final approval was received. By doing this the Contractor was able to progress dredging at the planned rate so that up to the end of Month-2 it was around 30% complete, and there was no actual delay to dredging.
The status at the end of Month-2 can therefore be shown in 2 ways. The first is shown in Figure-4a (using Progress Override) and 2nd in Figure-4b (using Retained Logic).
The most sensible view of status at the end of Month-2 is clearly that shown in Figure-4a. As soon as dredging commenced it became critical, and the ongoing late ‘formal’ approval of the dredging layout dropped off the critical path. The alternative view, shown in Figure-4b, is that progress of dredging was being critically delayed by late approval of the layout drawing. Moreover this delay already amounted to around 10 days. In this situation therefore, the Progress Override option provides the most sensible outcome.
Let’s now take the example a bit further. Assume that the dredging layout is finally approved early in Month-3, but the remaining dredging work is immediately suspended by the Engineer pending a comprehensive design review. Moreover this suspension remains in place up to the end of Month-6. Shortly after dredging is suspended, and with knowledge that this might last for several months, the Contractor carried out some preliminary filling work at the seawall trench. This was done to protect the small section of dredged trench from damage and siltation, and amounted to only 2% of the total filling. The 2 possible outcomes after rescheduling the programme are shown in Figure-5a (using Progress Override) and Figure-5b (using Retained Logic).
Figure-5a and 5b give a very different result compared to Figure-4a and 4b. This time the Retained Logic option produces the most sensible outcome (see Figure-5b). The occurrence of out-of-sequence filling in these circumstances should not override the prevailing logic. Clearly the critical issue affecting progress from the start of Month-3 to the end of Month-6 was the suspension to dredging, and this governed the earliest projected date for completing the Works.
The table below compares the different outcomes produced by the Retained Logic and Progress Override options. It is submitted that the most sensible result is that the 2 events have caused critical delay amounting to 110 days. Moreover this outcome is achieved by using a combination of the 2 scheduling options. Using only the Progress Override option underestimates the impact, whilst the Retained Logic function overestimates it.
The example above is a reminder that slavishly using one or other of the 2 scheduling options discussed here can lead to errors in defining the critical path, as well as the extent of critical path delays. If not treated carefully, this simple programming function can have significant consequences with respect to entitlement to time and money.
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Why is P6 the software tool of choice for planning?

Primavera allows for top level planning as well as being ideal for managing the intricate details. This enables project managers, planners, planning controllers and other associated professionals to have instant access to all the project information they require at the touch of a button. It also means that all parties can be kept updated within one system, reducing duplicate information and keeping everyone in the loop.

There are number of other P6 features which makes it unique and recommended tool for planning and will make a planner or a project manager life easier by providing structure, access to information, monitoring progress and reporting mechanisms capability:-


Perfect for Project-focused Business functions - Primavera project portfolio management solutions are also suited for any company with project-focused business functions such as Construction program management, Capital asset maintenance,  Software system development and deployment, Enterprise investment portfolio management, Resource productivity and capacity planning, Product design, manufacturing, and implementation program management etc.

High performance project management - The recognised standard for high performance project management Primavera handles large-scale, highly sophisticated and multifaceted projects. Organise projects of up to 100,000 activities with unlimited resources and an unlimited number of target plans. Enhanced fiscal accountability to customers to identify common scheduling pitfalls and quickly remedy them. Track costs and gain insight into change orders and forecasts. P6 allows top level planning as well as being ideal for managing the intricate details. All the parties can be kept updated within one system, reducing duplicate information and keeping everyone in the loop. Primavera P6 Implement sound risk management principles, reducing the risks associated with projects such as delays in delivery and resource shortages. It reduces risks of schedule inconstancies, errors, or overrun issues. P6 helps identify and mitigate risks in the course of planning and controlling projects. 

Optimized Resources – It helps to carefully monitor resource availability and adjust scare resources to meet project demand. Furthermore, the software can help identify areas where resource cost may be reduced by analysing trends and costs. Primavera has resource levelling option which is very handy in optimizing resources.

Enhanced visibility – Everything is included in the programme so you can easily see what’s going on with a project at any time.  It allows all data to be entered, tracked and analyzed in one location. An unified project view for all participants and stakeholders.

Improved Forecasting – Having up to date information means that you are able to clearly see where there is likely to be overbooked or underutilized resources and can plan accordingly. As the project progresses, the project may require additional resources/activities to meet stakeholder demand. Within P6 schedulers can create forecasts for resources, activities and other project needs.

Instant and Quicker access – Keeping track of progress with time and resources and getting information whenever and wherever needed. Usage of only one system which gives you all the information needed which saves time and cost by not having to refer different tools.

Tracking Features – The tracking features of Primavera P6 allows to rapidly generates wide range of reports

Enhanced Communication – Projects spanning large geographic areas requires hundreds of workers, engineers and many contractors. Primavera P6 enables executive staff to communicate with other stakeholders easily. Furthermore, notes can be made to the schedule in the software to ensure all users see the message.

Improved Collaboration – Since communication is enhanced throughout a project, it’s easy to see how improved communication translates into improved collaboration. 

Gives Employees user access in schedule creation/update- Site Engineers can create schedule, turn in timesheets and update progress.

"This blog is writen by Vishal K Singh, ProjCon. ProjCon is exclusive, niche and rapidly growing Project Controls Consultancy offering innovative, advisory, implementation, technical and training support to our Clients. Our consulting services enable effective use of Project Controls technology, methods and practices for EPC (Oil & Gas, Power, Defence and Infrastructure) industry customers worldwide.

Our comprehensive array of products and services provide powerful, affordable solutions to virtually all aspects of the Project Controls. Contact us to find out how we can help you to build/strengthen your Project Controls capability. For more info, visit us on"

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Why EPC Contracts are bound to be delayed


As the most common form of Contract for an industrial facility is an EPC Contract, we refer to EPC contractors, isn’it?

This is a little misleading I believe… and offers an opportunity to unveil what I believe to be a systemic cause to EPC Project delays.

One could imagine an EPC contractor to be a company covering the whole range of activities for the execution of a Project, from the drawing board to the pipe erection at Site.

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Critical path: Total Float vs Longest Path

Critical path: Total Float vs Longest Path


Oracle Primavera P6 offers two ways to define a critical activity in a project schedule. These are:

  • Total Float less than or equal to [0.0h]
  • Longest Path

Which one you use depends on three things. 1. the setting you choose in the Project view’s Settings tab: 2. the setting you choose in the Schedule Options dialog, and 3. that you understand the difference between the two options.  Primavera P6 defaults to the Total Float method.


This article is mostly about item three – what is the difference between Total Float criticality and the Longest Path? There’s some confusion about this in the industry because unfortunately the term “Critical Path” and “Longest Path” often get used interchangeably. In reality they are two distinct methods of calculating critical path and P6 can do either.

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Planning & Scheduling techniques

Let us first understand the terms i.e., planning & scheduling:
Planning is control of time on a project by:
•    Project Plans which optimise expenditure of time, recognise cost implications and reflect the contractual obligations for the design, procurement, construction and commissioning of plant facilities. 
•    Regular updates of all project activities and their inter relationships. 
•    Early indication of deviations from the approved project programme so that action can be taken to minimise their effect.
It is to be noted that key elements of plans are Scope of work and Method of execution including WBS.

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What is Project Plan


In order for any project plan to have a successful outcome, a foundational order of events must take place. Before any action can take place there must be the coming together of minds to brainstorm and produce a working project plan that will entail from start to finish how it will be done and in what duration it will be finished.

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Schedule updating

Contracts specify how a contractor’s entitlement to an extension of the project completion date due an event attributable to Company shall be determined:
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