Cost overruns in mining construction are not accidents - they are the predictable result of specific failures in estimates, risk allocation, and owner's team structure.
Cost overruns in mining construction are not accidents.
They are the predictable result of specific failures - in how estimates are built, how risk is carried, and how owner's teams are structured relative to the projects they are responsible for delivering. Understanding those failures is the first step toward avoiding them.
The Numbers Are Not Improving
Mining capital projects have one of the worst cost performance records of any industry. Studies of major mining projects consistently show that a significant proportion finish materially over their approved capital estimates - often by 30 to 50 per cent, and sometimes far more.
Schedule overruns compound the problem: a project that runs 18 months late is not just delayed, it is absorbing fixed costs, deferring revenue, and eroding the financial case that justified the investment in the first place.
These outcomes are not driven by bad luck. They are driven by patterns that repeat across projects, geographies, and commodities.
Where Estimates Go Wrong
The most common source of cost overrun is not a single catastrophic error - it is the accumulation of optimistic assumptions across a project estimate. Class 5 and Class 3 feasibility estimates are, by definition, built under uncertainty. The AACE International classifications acknowledge this: a Class 3 estimate carries an expected accuracy range of minus 10 to plus 20 per cent under ideal conditions. In practice, the conditions are rarely ideal.
Scope definition is frequently incomplete at the time an estimate is approved. Equipment pricing is based on budgetary quotes rather than firm commitments. Indirect costs - temporary facilities, logistics, mobilization - are underweighted relative to direct construction costs. And contingency, rather than being sized to the actual risk profile of the project, is often set at a round number that reflects what the project needs to look fundable rather than what the uncertainty actually warrants.
Owner's teams that rely entirely on contractor-produced estimates are particularly exposed. A contractor estimating its own work has structural incentives that do not always align with the owner's need for accuracy. The estimate that wins the contract is not always the estimate that reflects the true cost of delivery.
The Role of Independent Project Controls
This is where independent project controls change the outcome. An owner's team with its own cost intelligence capability - separate from the contractor, accountable only to the project owner - brings a different lens to the estimate and to ongoing cost performance tracking.
Independent project controls means reviewing estimates against comparable project databases before approval, not after the fact. It means tracking actuals against the approved baseline in real time, so variance is identified and understood while there is still time to act. It means asking the questions a contractor-aligned team may not be incentivized to ask:
Is this contingency sized to the risk?
Does this indirect cost envelope reflect what comparable projects have actually spent?
What does the schedule compression scenario do to unit costs?
These are not complicated questions.
They are often simply unasked - because no one on the owner's side has the data, the independence, or the mandate to ask them.
What Rigorous Cost Management Actually Looks Like
In practice, rigorous construction cost management at the owner's level has three components that most projects underinvest in.
The first is a defensible baseline. The approved project estimate needs to be documented at a level of detail that makes variance tracking meaningful.
A high-level summary budget is not a cost baseline - it is a number.
A true baseline maps cost to scope, to schedule, and to risk, so that when actuals diverge, the cause can be identified and isolated.
The second is continuous tracking.
Cost performance is not a monthly report. It is a live picture of committed costs, incurred costs, and forecast-to-complete, updated as the project moves, not assembled after the period closes.
Owner's teams that rely on contractor-produced monthly reports are always looking at last month's problem.
The third is portfolio context.
A single project's cost performance is difficult to assess in isolation. Owner's teams that can compare current project performance against a library of comparable completed projects - same commodity, similar scope, similar geographies- have a material advantage in identifying where a project is drifting before the drift becomes a variance.
The Owner's Responsibility
Cost overruns in mining construction are a systemic problem, but they are not inevitable. They are most common where owners have delegated cost intelligence to the parties least likely to surface uncomfortable information early.
The fix is not a better contractor. It is an owner's team with the capability, the independence, and the data to manage cost performance as a first-order responsibility - from estimate review through construction completion.
That is precisely the role Praetorian was built to fill.
Contact the team at info@praetoriancm.com to discuss how independent project controls can protect your next capital project.