The 12 Most Famous Project Budget Overruns in History

The most famous construction overrun in history. Jorn Utzon won the 1957 competition with a radical design -- radical to the point that nobody knew how to build the roof shells. Construction began in 1958 before the structural engineering was solved. The original AUD $7M budget was based on political pressure rather than engineering analysis.

Utzon's relationship with the New South Wales government deteriorated as costs escalated. In 1966 he resigned, and the interior was completed by a different team, meaning the acoustic performance of the concert halls was compromised. Final cost: AUD $102M -- 14.5 times the original estimate. Time taken: 16 years instead of the planned 4.

Primary failure: Construction started before design was complete. No realistic cost estimate existed. Political pressure to proceed trumped engineering reality.

The Central Artery/Tunnel Project in Boston remains the most expensive highway project in US history. The 1982 estimate of $2.8B grew to $14.8B by completion in 2007, with a further $7B in financing costs. The project ran 3 years late, and a section of ceiling collapsed in 2006, killing one person.

Key overrun drivers: underground Boston is full of historic utilities, foundations, and contamination that were not fully mapped. Cost-plus contracts gave contractors limited incentive to control costs. A series of design changes was approved without full cost impact assessment. The project also used an unusual delivery model for the time (design-build), which was not yet well understood.

Primary failure: Inadequate site investigation, cost-plus contracts without incentive for cost control, and 25 years of scope additions.

Berlin Brandenburg Airport became Europe's most infamous construction project. It missed its original 2011 opening date by nine years, finally opening in November 2020 -- too late and too small. The EUR 2B budget grew to over EUR 7B.

The most concrete failure: the fire suppression system failed inspection 66,000 times and had to be completely redesigned and reinstalled. The supervisory board approved constant design changes without understanding the engineering implications. There was no single, accountable project manager for much of the project's life -- responsibility was shared between government shareholders who had political rather than technical expertise.

Primary failure: Governance vacuum, design changes approved by non-engineers, defective systems installed and not caught until late inspection stages.

The UK's high-speed rail project from London to Birmingham is arguably the most politically contentious infrastructure project in recent British history. The original 2009 estimate for Phase 1 (London to Birmingham) was £37.5B. By 2024 the Phase 1 cost had risen to over £67B, with Phase 2 (Birmingham to Manchester and Leeds) cancelled entirely in October 2023.

The National Audit Office identified optimism bias in the original estimates, poor scope definition, and tunnelling cost underestimates as primary drivers. Design choices (high-speed specification requiring elaborate tunnelling through the Chilterns) added billions not reflected in early estimates.

Primary failure: Classic strategic misrepresentation -- the estimate was politically constructed to be low enough to secure approval rather than accurately reflecting the engineering reality.

The original 1997 estimate for what would become the James Webb Space Telescope was $500M with a 2007 launch target. By launch in December 2021, the actual cost had reached approximately $10B -- a 1,900% overrun. This is the largest scientific instrument budget overrun on record.

The technical complexity was genuinely unprecedented: a deployable 6.5-metre mirror operating at -233C in deep space, folded to fit inside a rocket, was beyond the engineering state-of-art in 1997. Multiple redesigns, contractor problems, and testing failures pushed the launch date back 14 years. The US Government Accountability Office (GAO) flagged the project as high-risk repeatedly.

Primary failure: Technical cause -- the original estimate was based on an immature design for technology that did not yet exist. Arguably an acceptable overrun given the scientific returns.