Government Project Budget Overruns: Why Public Sector Projects Always Cost More
Public projects have more scrutiny, oversight, and audit than private ones, yet they consistently overrun more. Understanding why requires understanding the political economy of project approval.
The Real Explanation: Strategic Misrepresentation
Professor Bent Flyvbjerg of Oxford's Said Business School provides the most honest explanation for government project overruns: many initial budgets are not genuine estimates. They are political constructs designed to be low enough to secure approval.
The mechanism is straightforward. A project champion (a politician, a promoter, a contractor) knows that the project would not be approved at its realistic cost. So the initial estimate is kept deliberately low. The project is approved and funded. Once construction begins, cancellation becomes politically and financially catastrophic: sunk costs, contractor commitments, and political embarrassment make it worse to stop than to continue spending. The project is "too big to fail."
This is not incompetence; it is rational self-interest for the individuals involved. The project promoter secures funding and careers are made. The overrun comes years later, long after the initial decision-makers have moved on. Flyvbjerg documents this pattern across hundreds of infrastructure projects spanning 20 countries.
Reference: Flyvbjerg, B. (2009). "Survival of the Unfittest: Why the Worst Infrastructure Gets Built, and What We Can Do About It." Oxford Review of Economic Policy, 25(3), 344-367.
UK Government Project Overruns
| Project | Original Estimate | Latest Cost | Overrun | Status |
|---|---|---|---|---|
| HS2 (now London-Birmingham only) | £15.8-17.4B (2010 plan, 2009 prices) | £87.7-102.7B (DfT May 2026, mixed price base) | about 5x to 6.5x | In construction; Phase 2 cancelled 2023 |
| Crossrail (Elizabeth Line) | £14.8B | £18.9B | 28% | Complete (2023) |
| Edinburgh Trams | £545M (2007, full line 1a) | £776.7M (shorter line; £835.7M with borrowing) | +43% | Complete (Phase 1, 2014) |
| Universal Credit (DWP) | £3.2B (implementation forecast) | £4.6B (NAO, July 2020) | +44% | Rollout planned for 2017; migration completed mid-2020s |
| NHS Patient Records (NPfIT) | £6.2B (2003-04 central contracts) | £9.8B (2013 forecast) | +58% (scopes differ) | Cancelled 2011 |
US Federal Project Overruns
| Project | Original Budget | Actual / Latest Estimate | Overrun |
|---|---|---|---|
| F-35 Joint Strike Fighter | $233.0B (2001) | $395.7B (2012); $482.7B (2025 estimate, FY2025 $) | +70% to 2012 |
| Healthcare.gov build contracts | $1.7B (60 contracts, value at award) | Obligations above award value on 20 of 60 by Feb 2014 | HHS OIG, Aug 2014 |
| Boston Big Dig (Federal Highway) | $2.6B (1985) | $14.8B (2007)æ9% | |
| FBI Virtual Case File | $170M | $170M spent, nothing delivered | 100% waste |
| James Webb Space Telescope (NASA) | $500M (1997 study) | $9.66B (2021 life-cycle estimate) | ~1,830% |
Frequently Asked Questions
Why do government projects always go over budget?
Government projects overrun for structural reasons beyond poor management. Flyvbjerg's theory of strategic misrepresentation explains that politicians and project promoters deliberately understate costs to secure approval. Once funded and started, cancellation is politically worse than overspending. Procurement rules that favour the lowest bid over the best plan compound the problem.
What is the UK government's record on major project costs?
The UK Government Major Projects Portfolio is tracked by the Infrastructure and Projects Authority, whose annual reports show many major projects running late and over budget. HS2: the London-Birmingham line alone is now estimated at £87.7-102.7B (DfT, May 2026, mixed price base), against £15.8-17.4B in the 2010 plan (2009 prices). Crossrail: from a £14.8B budget in 2010 to a £18.9B forecast (NAO 2021). Universal Credit: implementation cost forecast up from £3.2B to £4.6B (NAO 2020). Edinburgh Trams: £776.7M for a shorter line than the £545M 2007 budget covered (Edinburgh Tram Inquiry 2023).
What is the GAO High Risk List?
The US Government Accountability Office (GAO) maintains a biennial "High Risk List" of federal programs with persistent cost, schedule, or management problems. Defence acquisition programmes consistently appear. Being on the High Risk List signals systemic governance failure. The GAO's reports are publicly available and are the primary source for US federal project overrun data.