Tracking the Procurement Process Using a CPM Schedule

Why procurement belongs in the schedule

Construction schedules often model only field work, treating materials as if they'll "be there." But on real projects, procurement is frequently what controls the finish — a long-lead item ordered too late can delay installation no matter how fast the crews are. Putting procurement in the network closes that blind spot.

The procurement chain

Each significant purchased item carries its own little chain of activities, ending at the field installation it feeds:

1. Requisition & specify — engineering defines and requisitions the item — itself often dependent on design progress.
2. Purchase order — bid, evaluate, award, and place the PO — the commercial step that starts the supplier's clock.
3. Fabricate / manufacture — the supplier's lead time — for long-lead items, the dominant duration in the whole chain.
4. Ship & deliver — transport, customs, and on-site receipt — ending at "material on site," ready to install.

Long-lead items & reverse planning

The items that wreck schedules are the long-lead ones — transformers, switchgear, large pumps, specialty steel — whose fabrication runs many months. For these, you plan backwards from the need date: when must it be on site to install on time, and therefore when must the PO be placed and the requisition issued?

Reverse planning makes the risk concrete: if a transformer needs 30 weeks and must be installed in month 12, the PO must be placed by month 5 — which means the requisition and design must be done even earlier. Model that chain and the schedule tells you, in month 4, that you're about to be late — while there's still time to expedite.

Tracking procurement through updates

Once procurement is in the network, it gets statused like any other work: requisitions issued, POs placed, fabrication progress, shipping milestones — all updated each period so the forecast reflects real supplier status.

Ten things to remember

1. Put procurement in the CPM — requisition, PO, fabrication, delivery as linked activities.
2. Procurement often controls the finish — not just labour. Model it or stay blind to it.
3. EPC's "P" is a full phase — its lead times can dwarf construction durations.
4. Link delivery to installation — material-on-site is a predecessor to the field activity.
5. Long-lead items are the ones that bite — transformers, switchgear, specialty steel.
6. Plan backwards from the need date to set the required order-by date.
7. Carry an order-by milestone for every long-lead item — in the CPM, not just a log.
8. Status procurement each period — POs, fabrication, shipping — like any other work.
9. Watch when a supplier is on the critical path — then a delivery, not a crew, runs the project.
10. Early visibility buys options — expedite, resequence, or find an alternate before crews idle.