英国高速铁路二号线（HS2）预计总成本可能超过1000亿英镑，按单位公里计算将成为全球最昂贵的铁路项目。该项目最初于15年前提出，计划连接伦敦、利兹和曼彻斯特，但目前线路长度已大幅缩减。2024年价格计算的官方最新估算约为800亿英镑，经购买力平价调整后，单位成本约为每公里5.37亿美元，比日本Chuo Shinkansen高出26%，在涵盖94条线路的国际数据集中排名第一。项目迄今已花费逾400亿英镑，纳税人每年承担约70亿英镑，即每周约1.4亿英镑。
成本失控的关键原因之一是治理与合同结构。2009年成立的HS2 Ltd在早期将大量项目管理权交由承包商，采用“成本加成”合同，支出越高，承包商收入越高，直接削弱了成本约束。英国交通部监督不足，网络铁路公司角色被边缘化。2025年由前基础设施英国负责人James Stewart撰写的政府报告指出，技术能力不足的官员与承包商权力过大形成结构性失误。相比之下，日本由Japan Railway Construction, Transport and Technology Agency集中负责规划、成本控制和施工审查，能够在地质或设计变更时理性调整预算。
项目雄心与设计选择进一步推高成本。HS2被锁定为西方世界最快的常规铁路，设计时速400公里，比欧洲标准高约三分之一，导致更多隧道、高架桥和土方工程。环境与建筑“定制化”亦显著增加支出，例如为保护蝙蝠建造的1.19亿英镑隧道，以及包含约1000个独特构件的科尔恩谷高架桥。尽管新任首席执行官Mark Wild承诺在2025年重整预算和合同，但伦敦尤斯顿终点站连接延误已造成至少2亿英镑的额外成本，项目仍被视为高成本、低效率决策的集中体现。
The UK’s High Speed 2 (HS2) is projected to exceed £100bn in total cost, making it the most expensive railway ever built on a per-kilometre basis. Announced more than 15 years ago to link London, Leeds and Manchester, the line has since been sharply curtailed. The last official estimate, about £80bn in 2024 prices, implies a PPP-adjusted cost of roughly $537mn per km, around 26% higher than Japan’s Chuo Shinkansen and the highest among 94 international projects. More than £40bn has already been spent, with taxpayers paying about £7bn per year, or £140mn per week.
A central driver of overruns has been governance and contracting. HS2 Ltd, set up in 2009, embedded contractors as project managers and relied heavily on cost-plus contracts that rewarded higher spending. Oversight by the Department for Transport was weak and Network Rail was sidelined. A 2025 government-commissioned review by former Infrastructure UK chief James Stewart found excessive power concentrated among contractors and officials lacking technical expertise. In contrast, Japan assigns planning, cost control and construction review to the Japan Railway Construction, Transport and Technology Agency, enabling disciplined budget adjustments when geology or design changes arise.
Ambition and bespoke design further inflated costs. HS2 was locked in as the fastest conventional railway in the western world, with a 400 kph design speed—about one-third above European norms—requiring flatter alignments, more tunnels and viaducts, and higher-specification structures. Environmental and architectural choices added to the bill, including a £119mn bat-protection tunnel and the Colne Valley Viaduct with around 1,000 unique segments. Although chief executive Mark Wild has pledged to reset budgets and contracts during 2025, delays at the Euston terminus alone have officially cost at least £200mn, leaving HS2 emblematic of extreme cost escalation.