Schedule Diagnostics

Introduction

Nearly a decade ago I was working in a role that involved reviewing schedules regularly. and there were not many schedule metrics/diagnostics (think DCMA 14pt) tools available. Of those that were, most only considered these metrics at an aggregate level, for the entire schedule.

Using data exports and considerable effort in Excel, I came up with my own set of diagnostics, with more focus across the full timescale of the schedule,

I'm presenting them below as inspiration for others to use them also.

I'm still of the opinion that these checks offer very little information about the "quality" of a schedule, as they do not address the scope of work the schedule represents, however, for a quick and repeatable diagnosis of a schedule, they can sometimes elevate issues for investigation.

Activity Count

• Indicators: Count of Activities in progress over time periods, the number of critical activities in each time period and the cumulative number of activities starting and finishing?
• Analysis: The distribution of schedule activities project timescale, the % and distribution of activities that are critical, and a measure of the number of activities occurring in parallel

Duration Analysis

• Indicators: Duration of activities occurring over time periods by category and the number of critical activities in progress in each time period.
• Analysis: Indicates the duration range of activities covering each time period, Can indicate presence of high-duration activities that cover longer time periods

Duration vs Float

• Indicators: Duration and Float for all activities in schedule, Set thresholds for acceptable duration and float values and the number of activities that meet those thresholds
• Analysis: Identify tasks with high duration and/or high float, and count the number of activities that meet or exceed thresholds

Constraint Analysis

• Indicators: Indicates constraints in schedule including, current schedule date vs constraint date, indicates type of constraints applied and balance line indicating whether activity date is on constraint date or earlier/later?
• Analysis: Can indicate excessive usage of constraints, indicate whether constraint dates are being upheld or exceeded/improved, and identify clustering of constraints by time period

Logic Type

• Indicators: Type of logic used in schedule, distribution of logic time over time periods, and total count of logical relationships over time period
• Analysis: Indicates the type of relationships used in the schedule, can indicate excessive usage of any particular type of relationships, and check of the quality of SS – FF closed logic

Logic Analysis

• Indicators: Indicates the number of relationships occurring?over time periods, indicates activities with no predecessors or no successors and when these occur, and a measure of Logic density
• Analysis: Logic Density: eg (number of predecessor links/ number of activities starting – Minimum should be 1)

Lag Analysis

• Indicators: Indicates relationships with lag values, Indicates use of lags over time periods, and Indicates the value of the lag for each relationship
• Analysis: Can indicate existence of lags driving activities (rather than relationships), and indicates type of links that lags are used on

Logic Density

• Indicators: Activities with High number of relationships (eg, greater than five predecessors or successors), when these high relationship activities occur in time, indication of how many of the relationships are driving
• Analysis: Can identify occurrences of high density logic “merge spots”, and also indicates whether these network nodes drive subsequent activities

Free Float + Total Float effort

• Indicators: Measure of the Free Float + Total Float in progress in time periods , overlaid with Duration Effort
• Analysis: Indicates to what extent free float is available as part of the total float in the schedule

Duration + Float Effort

• Indicators: Measure of the Duration + Total Float in progress in time periods, Cumulative Duration + Float effort, and Overlaid with Duration Effort
• Analysis: If schedule contains minimal float, can expect to see little difference between duration effort and Float effort, and can indicate a high “build up” of float

In Practice

So how does the use of the above work? Lets take a look at one of these diagnostics across a different range of projects, and some of the questions that can be raised.

Activity Count

As the above shows, there is a wide range of possible results when viewing this type of diagnostic data, but how useful is it? The Airport project warrants an investigation into why there are no critical activities in the early part of the project. The Powerline project may beg the question as to why there are such a high number of critical activities in the middle of the project.

Note also the profiles clearly show that some schedules have a high number of activities early in the project, most likely to be design, so has the scope of the work been covered adequately for the latter works?

What Next?

The use of Schedule metrics/diagnostics is now common practice, I re-iterate that such analyses should only represent a very small part of review and investigation of a schedule. The above do not concern themselves with the nature of the project, the type of work they represent and the underlying assumptions made in developing the schedule, this is where effort is to be made to thoroughly review a schedule.

Software that readily creates metrics and diagnostics is readily available now, however I have rarely seen such metrics presented as above, perhaps consideration for future releases? For myself, my 2022 goal is to re-create the above while learning to use Power BI to make these outputs more interactive.