Why Big Projects Run Late and Over Budget

Why infrastructure megaprojects around the world so often exceed their budgets and timelines, the causes in India, and how planning can improve.

Around the world, big infrastructure projects are famous for running late and over budget.

The iron law of megaprojects

Oxford professor Bent Flyvbjerg studied thousands of large projects and described an “iron law of megaprojects”: over budget, over time, under benefits, over and over again. His research found that the large majority of megaprojects exceed their budgets.

Why it happens

Optimism bias: planners underestimate costs and overestimate benefits.
Strategic misrepresentation: some supporters understate costs to get projects approved.
Complexity: large, unique projects face unexpected problems.
Scope changes after work begins.
Coordination among many agencies and contractors.

India’s experience

India’s Ministry of Statistics and Programme Implementation monitors large central projects. Its reports have repeatedly shown that many projects are delayed and a significant share face cost overruns. Common causes include:

Land acquisition problems.
Environmental and forest clearances.
Funding delays.
Contractual disputes and litigation.
Law and order issues in some regions.

The costs of delay

Higher costs from inflation and interest during construction.
Delayed benefits: a road that opens five years late loses five years of benefits.
Stranded investments: money tied up without returns.

Better planning

Reference class forecasting: estimating costs based on the actual outcomes of similar past projects, rather than optimistic plans.
Clearances before work begins, including land.
Modular design: breaking projects into smaller, repeatable parts, like solar farms, which tend to have fewer overruns.
Digital monitoring: India’s PRAGATI platform and PM Gati Shakti aim to coordinate approvals and track progress.

The delayed rail line

A railway line planned for five years takes eleven. Land disputes, forest clearance and contractor changes each add delays, and the cost doubles. Meanwhile, businesses that expected the line wait years for the benefits.

Thinking overruns are always caused by corruption

Corruption can play a role, but optimism bias, complexity and clearance delays are common causes worldwide.

Key takeaways

Most megaprojects worldwide exceed budgets and timelines.
Optimism bias, misrepresentation and complexity drive overruns.
In India, land, clearances and funding are frequent causes.
Reference class forecasting and early clearances improve outcomes.