What Is the Half-Step in Forensic Delay Analysis? How Plannex Automates MIP 3.4

For delay analysts, planners, and claims professionals, one of the biggest problems in retrospective schedule analysis is that a single update often contains two very different things at the same time: actual project progress and schedule revisions. When those two are mixed together, it becomes harder to answer a critical forensic question: Was the project delayed because the work progressed slowly, or because the plan itself was changed?

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The Half-Step is the practical answer to that problem. In AACE RP 29R-03, this concept sits within MIP 3.4 — the Bifurcated / Split Contemporaneous Period Analysis method.

What is the Half-Step in forensic schedule analysis?

The Half-Step is a bifurcation procedure used in forensic schedule analysis to separate progress-only effects from non-progress revisions inside a schedule update.

In simple terms, instead of accepting an updated schedule exactly as submitted, the analyst first creates an intermediate schedule that reflects only actual progress. After that, the analyst compares this progress-only version with the full updated schedule to identify the effect of revisions.

This is why MIP 3.4 is commonly called a Split Contemporaneous Period Analysis or Bifurcated Analysis.

According to the methodology, MIP 3.4 is generally understood as:

• Retrospective — used after delays have occurred
• Observational — based on the project schedules as they existed, without modeling delays by adding fragnet activities
• Dynamic — because the critical path can change from one update to another
• Contemporaneous — because it relies on the schedule updates that were in effect during project execution
• Split / Bifurcated — because each analysis window is divided into two half-steps: progress first, revisions second

Why the Half-Step matters

This method matters because schedule updates often include far more than field progress. They may also include:

• logic changes
• added or deleted activities
• changed relationships or lag values
• calendar changes
• constraint additions or modifications
• original duration changes
• other planning revisions made to mitigate, resequence, or reshape the remaining work

If these revisions are not separated from actual progress, they can:

• mask the true effect of slow progress
• shift the apparent critical path
• make delay ownership less clear
• create the false impression that no delay occurred in that period

That is exactly why the Half-Step is so important in forensic delay analysis. It helps the analyst distinguish between:

• delay caused by actual project performance, and
• gains or losses caused by revisions to the schedule model

In practice, this often reveals that a project lost time due to progress, and then “recovered” that time only because the scheduler shortened future durations, changed logic, or resequenced remaining work.

How the Half-Step relates to AACE RP 29R-03 and MIP 3.4

AACE RP 29R-03 provides the taxonomy and implementation guidance for forensic schedule analysis methods. Within that framework, MIP 3.4 is the method used when the next schedule update includes both actual progress and schedule revisions.

The core idea is straightforward:

1. Start with the previous update, often called the Beginning of Period (BOP) schedule.
2. Copy that schedule.
3. Insert progress only from the next update into the copied schedule.
4. Recalculate using the next data date.
5. This produces the temporary Half-Step or progress-only schedule.
6. Then compare that Half-Step schedule with the full next update to identify the effect of revisions.

This two-stage comparison allows the analyst to evaluate each window in a more disciplined way:

• BOP → Half-Step = what happened because of progress only
• Half-Step → Updated Schedule = what changed because of revisions

That is the major distinction between MIP 3.4 and MIP 3.3. MIP 3.3 assumes the update can be analyzed as-is. MIP 3.4 goes one step further and separates revisions from progress before drawing conclusions.

The manual implementation: technically sound, but time-consuming

From a forensic perspective, the manual method is powerful. But from a practical perspective, it can be very time-consuming.

To implement the Half-Step manually and correctly, the analyst usually needs to:

• validate the baseline and update schedules
• confirm actual dates and progress data against project records
• copy the previous update
• transfer actual starts, actual finishes, remaining durations, and status data carefully
• preserve the original logic structure while importing progress
• recalculate with the proper data date
• compare progress-only results against the full update
• identify revision impacts on the critical path
• document delays, gains, mitigation, and possible critical path shifts for every analysis window
• repeat the same process update after update across the life of the project

And if the analyst wants to go even deeper using an enhanced daily progress method, the effort increases dramatically.

Why manual Half-Step work often becomes difficult in real projects

In real-world projects, the challenge is not only the analysis logic. The challenge is the workload.

Many planners and claims teams face situations like these:

• monthly updates contain both field progress and planning revisions
• consultants ask for a clean progress-only XER for later claims review
• schedules contain hundreds or thousands of activities
• activity codes, resources, and expenses need to remain consistent
• multiple analysis windows must be processed quickly
• errors in one manual copy can affect the credibility of the entire analysis

That is why the manual approach, although correct in theory, often becomes slow, repetitive, and vulnerable to human error.

A practical example from claims and forensic review

A very common claims situation is when the consultant or delay analyst wants to separate the update into two versions:

• one version that reflects the schedule as fully updated, including revisions
• another version that reflects progress only, without revised logic contaminating the result

This becomes especially important when preparing for a future claim, reviewing contemporaneous updates, or assessing whether mitigation shown in the update was real progress or only a planning revision.

In many projects, that means the team ends up preparing two XER files for each period:

1. a normal updated schedule containing revisions
2. a progress-only version to support Half-Step review

Doing that manually every update can take significant time, especially when repeated month after month.

How the Plannex Half-Step Tool solves the problem

This is where the Plannex Half-Step Tool becomes highly practical.

The tool is built to automate the progress-only Half-Step XER creation process. Instead of manually rebuilding the progress-only version activity by activity, the tool reads:

• the original schedule XER, and
• the updated schedule XER

Then it produces a new progress-only XER while preserving the original logic structure.

In other words, it helps create the first half of the bifurcation quickly and consistently.

What the Plannex Half-Step Tool does

Based on the tool workflow, Plannex can:

• match activities between the original and updated XER files
• transfer progress fields such as status, actual dates, remaining duration, and percent complete
• preserve the original logic structure to avoid revision contamination
• carry over resource assignments and expense values when available
• generate a fresh output XER ready for review in Primavera P6
• flag unmatched activities, blank codes, and skipped fields for QA review

This makes the tool especially valuable for teams who need a reliable progress-only update without manually rebuilding the schedule every time.

A simplified workflow using Plannex

A practical workflow can look like this:

1. Export the previous or original schedule from Primavera P6 as XER.
2. Export the updated schedule as XER.
3. Open the Plannex Half-Step Tool.
4. Select the original XER.
5. Select the updated XER.
6. Choose the save location.
7. Generate the Half-Step XER.
8. Import the output file into Primavera P6 for review.
9. Compare the progress-only schedule against the full update to identify revision impacts.

This does not eliminate forensic judgment. The analyst still needs to review critical path behavior, investigate delay drivers, validate records, and assign responsibility. But it significantly reduces the repetitive manual effort needed to produce the progress-only schedule itself.

Why this matters for professional delay analysis

A good forensic schedule analysis is not only about using the right theory. It is also about building a workflow that is:

• accurate
• transparent
• repeatable
• defensible

The Half-Step under MIP 3.4 is one of the clearest ways to isolate actual progress from schedule manipulation, mitigation revisions, or planning changes. And when this process is automated properly, the analyst can spend less time on file preparation and more time on what actually matters:

• understanding critical path movement
• identifying delay causation
• evaluating responsibility
• presenting conclusions clearly

That is where Plannex adds real value. It does not replace the analyst. It strengthens the analyst’s workflow.

Final thoughts

If your project updates contain both progress and revisions, then analyzing the update “as-is” may not be enough. The Half-Step approach under AACE RP 29R-03, MIP 3.4 provides a more disciplined and forensic way to understand what really happened in each period.

Manually, the method is strong but labor-intensive.

With the right workflow, however, the process becomes much more practical.

The Plannex Half-Step Tool helps teams generate the progress-only XER faster, preserve original logic, and prepare cleaner schedules for claims review, delay analysis, and forensic reporting.

If you work in planning, project controls, claims, or forensic delay analysis, this is one of the most useful schedule workflows you can add to your toolkit.

Watch the tool in action

• Arabic video: https://youtu.be/4wjHI01XIBo
• English video: https://youtu.be/YBCE9NJJ_Xc

Try the tool

• Plannex Tool: https://plannexcg.com/plannex-tool/
• Telegram group: https://t.me/Plannex_group