Unit-rate build-up in construction bids: productivity, crews, equipment and indirect cost

A unit rate is not simply a market price per cubic metre, tonne or metre. It is a production model. The estimator should identify what physical activity is being measured, what the measurement rule includes, which temporary or ancillary works are deemed included, and what production method will be used to achieve the required specification and acceptance criteria.

Labour cost begins with crew structure and productive hours, not payroll divided by output. Travel, breaks, access, permits, shift changes, weather, learning curves, congestion, rework and supervision affect effective productivity. For repetitive work, the estimate should distinguish theoretical output from achievable sustained output and record the productivity basis that management accepts.

Equipment rates should combine ownership or rental cost with fuel, operators, maintenance, tyres or wear parts, mobilization, standby, utilization and cycle time. Excavation and haulage are especially sensitive to loading time, haul distance, road condition, dumping time and return cycle. A change in haul route can invalidate a rate even when the excavation quantity itself is unchanged.

Material rates should account for purchase price, wastage or yield, transport, storage, handling, testing, rejection risk and installation losses. Imported materials add Incoterms, freight, insurance, customs, duties, inland transport, currency and lead-time assumptions. The cheapest ex-works quotation can therefore produce a higher installed unit rate than a more expensive regional source.

The estimator must then decide where indirect cost belongs. Some project overhead is best carried in preliminaries because it is time-related; other support costs can be distributed across production items if the BOQ and commercial strategy require it. The allocation method should not hide the fact that a quantity reduction can leave time-related overhead largely unchanged while reducing the revenue over which that overhead was spread.

A strong bid review therefore tests the few rates that dominate project value or risk rather than checking every rate with the same intensity. High-quantity earthworks, concrete, reinforcement, pavement, structural steel, piping, cable and other key production items should be subjected to productivity and quantity sensitivities. The objective is to identify which assumptions can move the tender margin before the project moves them after award.