“Avoiding Common NSMM Pitfalls: Lessons Learned from Lagos Road and Bridge Works”

1. Misclassifying Provisional Sums

The Issue: On large road contracts, provisional sums for unexpected soil conditions or utility relocations often end up buried without proper identification.Case Study: During the Lagos–Badagry upgrade, several provisional sum items weren’t flagged clearly in the BOQ, leading to delayed approvals and cost disputes.Tip: Create a dedicated “Provisional Sums” section in your BOQ. Label each entry with NSMM codes and a brief note on its scope. This clarity helps clients and subcontractors track and agree on those costs before work begins.

2. Neglecting Waste Allowances

The Issue: Concrete batching plants and asphalt producers in Lagos Island reclamation projects apply standard waste percentages—but surveyors sometimes forget to include NSMM’s prescribed allowances.Case Study: On a bridge approach slab, actual concrete orders exceeded estimates by 7% due to overlooked waste factors, hurting the contractor’s margins and delaying site mobilization.Tip: Refer to NSMM’s waste guidance when you quantify materials. Even if local practice uses 5% for waste, confirm that it aligns with NSMM tables. Document your assumed percentage in the BOQ remarks field.

3. Incorrect Unit Application

The Issue: Steel reinforcement on bridge piers should use “tonnes” (t), yet some engineers slip into listing it as cubic metres (m³), confusing weight with volume.Case Study: During foundation piling for the Lekki–Ikoyi Link Bridge, reinforcement steel was listed incorrectly, forcing rework of subcontractor invoices.Tip: Double-check every steel item’s unit code against NSMM. A quick scan of your spreadsheet for any “m³” in the steel section can catch these mismatches before they become costly.

4. Overlooking Site-Specific Clauses

The Issue: Lagos bridge works often include tidal-water mitigation or night-work premiums, but these special conditions aren’t always reflected in the standard NSMM rules.Case Study: A flood-protection wall along Eko Atlantic’s new road was billed under generic earthworks, omitting the premium rate and creating payment delays.Tip: Always review your contract’s special specifications alongside NSMM. If the contract mentions a surcharge for tide-dependent works, treat it as a separate BOQ line with its own unit and rate.

5. Incomplete Variation Logs

The Issue: Road widening schemes in Lekki Phase 1 saw numerous design tweaks—from carriageway alignment to drainage details—but surveyors often recorded only headline variation values.Case Study: Without detailed VS logs, multiple small changes got lumped into a single claim, triggering client pushback on justification.Tip: Maintain a running variation schedule with clear descriptions, NSMM codes, and date stamps. Link each variation back to supporting drawings or correspondence so that your client can see exactly what changed and why.