Rolling Wave Planning
Last reviewed 9 September 20261,706 words8 min read
Detail near, summary far — without hiding scope
🟩 In one line: Detail the next 3–6 months at Level 3 and hold everything beyond it as coded, budgeted Level 2 planning packages that you convert one update ahead of their wave — never as a blank space labelled "TBC".
👤 Who this is for: Mid-level planners on design-led or long-duration jobs. Prerequisites: Schedule-levels-1-to-5, Wbs-structure-design, Activity-duration-limits.
First, let's be honest about why this page exists
Rolling wave is a respectable idea that gets used as an excuse. "We'll detail that later" becomes a 180-day bar called "Fit-out Levels 3–9" that nobody ever detailed, and by the time someone opens it the float it was hiding is gone.
On most Gulf lump-sum contracts the specification demands a full Level 3 baseline anyway, so rolling wave is not a way to avoid building the schedule. It is a way to manage scope whose design or method is genuinely not fixed yet — fit-out, medical equipment, ICT, T&C sequences, later phases of an EPC job — and to keep Level 4 honest.
🟨 The standard — what "good" looks like
| Source | What it says (paraphrased) | Use it for |
|---|---|---|
| PMI Practice Standard for Scheduling, 3rd ed. | Rolling wave is progressive elaboration: near-term work detailed, far-term work as planning packages with defined scope and budget (check against your copy) | Definition |
| AACE RP 37R-06 Schedule Levels of Detail | Levels 1–5 defined; a schedule may hold different levels for different time horizons if declared | Justifying L3 near / L2 far |
| GAO Schedule Assessment Guide (GAO-16-89G), Best Practice 1 | All scope captured; planning packages acceptable if scoped, budgeted and scheduled for conversion | The "no hidden scope" test |
| DCMA 14-Point Assessment, item 8 (High Duration) | Activities > 44 working days flagged; planning packages are the recognised exception when identified | Why packages must be coded |
| FIDIC 1999 Cl 8.3 / 2017 Cl 8.3 | Programme covers the whole Works; revised programme when the current one is inconsistent with actual progress or obligations (check the edition in your contract) | Full scope in the baseline, conversions as revisions |
| NEC3 Cl 31.2 / 32; NEC4 Cl 31.2 / 32 | Programme shows order and timing of operations; revised programme submitted at the Contract Data interval | Conversions happen in the periodic revision |
| Hub convention | Detail horizon 3–6 months (4 for buildings). L3 production 5–20 days, none > 44 without reason. L3 = contract baseline. | Your defaults |
🟢 Rule: a planning package is a real activity with a WBS node, a quantity, a manhour budget, real logic and a conversion date — or it is a hole in the schedule.
How it actually works
1. Decide the horizon and write it down. Buildings: 4 months of L3 ahead of the data date; EPC early phase: 6 months; shutdowns: the whole event at L4 (no rolling wave). Put the horizon in the SBM exceptions table with the list of scopes it applies to.
2. Build the package, not a bar. One Task Dependent activity per package, under its own WBS leaf node, named "[Scope] — planning package".
| Attribute | Setting |
|---|---|
| Duration | Manhours ÷ (planned crew × hours/day), rounded up — same formula as any activity |
| Duration / % type | Fixed Duration & Units / Physical % |
| Logic | Real FS in from the last detailed predecessor; real FS out to the next interface |
| Activity code Detail Status | PKG (placeholder) → DET (converted) |
| UDF Detail By DD | The data date by which conversion must be done — package early start minus one horizon |
| Notebook WBS Scope | What is in the package, what is out, the quantities |
| Constraints | None |
3. Convert one update ahead of the wave. At each update, filter Detail Status = PKG and Early Start ≤ DD + horizon + one period. Those packages get converted before the next submission.
| Step | Action |
|---|---|
| a | Create a Reflection of the last accepted update |
| b | Under the package's WBS node add the L3 activities (durations from the SBM basis tables, logic hard first, then SOFT-RES/SOFT-PREF labelled) |
| c | Check the detailed activities' manhours sum to the package budget; a difference > 5 % is a change-table row with a reason |
| d | Move the package's predecessors to the first detailed activity, successors to the last; Dissolve the package activity (never Delete) |
| e | Code the new activities Detail Status = DET, Split From = package ID |
| f | Reschedule; run Schedule Comparison against the source. The package finish should not move later. If it does, that is a slippage with a cause tag, not a "conversion effect" |
| g | Archive comparison; list the conversion in the narrative change table under planner edits |
4. Keep the mapping. Package ID → detailed activity IDs, in the SBM split-mapping table, so BEI in the transition month is measured on the mapping.
⚖️ Contract note. Rolling wave does not reduce the scope the programme must show (FIDIC Cl 8.3; NEC Cl 31.2). Float sitting inside a package is real float and belongs to whoever the contract says owns it. If the client specification demands a full L3 baseline, the packages are Level 4 placeholders under a complete L3 — not L2 placeholders under a partial L3.
🟥 Where people go wrong
- The package has no quantity. "Fit-out L3–L9, 180 days" with no manhours behind it cannot be tested, cannot be resourced and cannot be converted honestly. No budget, no package.
- The conversion comes out longer and nobody says so. The 66-day package becomes 84 days of detail and the narrative calls it "refinement". It is duration growth; tag it and diagnose it.
- The horizon is whatever this month felt like. Three months in March, one month in July. Fix the horizon in the SBM and filter on it every update.
- Packages get logic to WBS Summary or LOE activities. They then float free of the real work. Packages link to real production activities at both ends, like everything else.
- Rolling wave used on a contract that requires full Level 3. The client rejects the baseline in week two. Read the specification's activity-count and duration clauses before proposing packages.
- Package deleted instead of dissolved. The in and out logic vanishes and the detailed activities dangle. Dissolve keeps the chain; then move the ends.
⚖️ When you're challenged
"Why is half your schedule in 60-day bars?" Because the design for that scope isn't frozen and detailing it now would be invention. Every bar has a WBS node, a quantity, a manhour budget and a conversion date in the schedule. The next wave converts at the March update.
"You just added 200 activities — what changed?" Nothing on the dates: the Schedule Comparison archived with the submission shows the package finish unchanged. The 200 activities replace one package under the same WBS node with the same budget; the mapping table is in the narrative.
"Isn't this just hiding float?" The opposite. The package sits on real logic and its total float is visible in layout 04 like any activity. When it converts, the float distributes across the detail; it doesn't appear or disappear.
📄 Related pages
- Schedule Levels 1 to 5 — what L2 and L3 mean here
- Activity Duration Limits — the 44-day flag and the exceptions table
- WBS Structure Design — the package's WBS node and the 100 % rule
- Splitting In-Progress Activities — the same mapping discipline, used for a different reason
- Change Control in a Live Schedule — conversions go in the change table as planner edits
- P6 Reflections and What-If — where the conversion is done
- Engineering and Design Schedule — why the design chain decides when a package can convert
✏️ Worked example — Riyadh hospital, medical fit-out packages
DD 25-Feb, horizon 4 months, conversion window to 25-Jul.
| Package ID | Scope | Budget mh | Dur (d) | Early Start | Detail By DD | Status |
|---|---|---|---|---|---|---|
| PKG-L3-RAD | Radiology L3 fit-out | 7,920 | 66 | 12-Jun | 25-Feb | Convert now |
| PKG-L4-OT | Operating theatres L4 | 11,400 | 76 | 03-Aug | 25-Mar | Next update |
| PKG-L5-ICU | ICU L5 fit-out | 6,480 | 54 | 21-Sep | 25-May | Later |
| PKG-MEQ-2 | Medical equipment install, Phase 2 | 4,200 | 42 | 14-Nov | 25-Jul | Later |
Converting PKG-L3-RAD (66 days, 7,920 mh, crew 12 × 10 h):
| New activity (extract) | Dur (d) | Logic basis |
|---|---|---|
| Radiology L3 — set out & first fix MEP containment | 8 | FS from package predecessor (L3 slab handover) |
| Radiology L3 — lead-lined partitions Zone A / Zone B | 12 / 12 | Zone B SS+6 on Zone A (SOFT-RES, same crew) |
| Radiology L3 — ceiling grid & second fix | 14 | FS partitions Zone B |
| Radiology L3 — flooring & doors | 10 | FS second fix |
| Radiology L3 — equipment pre-installation checks | 6 | FS flooring; FS out to MRI delivery milestone |
Fourteen activities in total; manhours sum 8,040 (+1.5 %, within tolerance); longest chain 66 days; package finish 27-Aug unchanged. Schedule Comparison shows zero date change on all other activities. Change table: one planner-edit row, "PKG-L3-RAD converted to 14 activities, mapping in SBM Table 12-4".
📖 References
- PMI, Practice Standard for Scheduling, 3rd ed. (check the edition and section in your copy)
- AACE International RP 37R-06, Schedule Levels of Detail — As Applied in Engineering, Procurement and Construction
- GAO, Schedule Assessment Guide, GAO-16-89G, Best Practice 1
- DCMA 14-Point Schedule Assessment, item 8
- FIDIC Conditions of Contract 1999 and 2017, Cl 8.3 (check the edition in your contract)
- NEC3 / NEC4 ECC, Cl 31.2, Cl 32 (check the edition in your contract)
- Oracle Primavera P6 Professional User Guide — Dissolve activity; Reflections (check against your P6 version)
From the field
Experience from working planners. Unreviewed — read it as experience, not guidance.
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