Case study

Crossrail (Elizabeth line)

Optimistic resets

What happened

London’s Crossrail central section slipped past its planned date. The UK National Audit Office reported in 2021 that the estimate had reached £18.9 billion, that contractors met only about 30% of milestones on average, and that plans assumed more productivity than was achieved.

Why it matters

Reset plans were built on optimism instead of demonstrated productivity, and the project was further from finished than anyone understood.

Lessons

• Base recovery plans on demonstrated productivity.
• Plan hand-over early.
• Revisit benefits as the world changes.

Tools for this

• Reference Class Forecasting
• Monte Carlo Simulation
• Benefits Realization Plan

Sources

• UK National Audit Office, Crossrail – a progress update (2021)

Last reviewed 2026-11-02. “Why it matters” is our reading of the sources.

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